Heimdal

The first interpretation:

Heimdall and the rainbow bridge, how do they exist in Norse mythology? Heimdall is a god who guards the Bifröst, the rainbow bridge that connects Asgard, the realm of the gods, and Midgard, the realm of the humans. He is said to have nine mothers, who are sisters and daughters of the sea god Aegir. He has keen senses, especially his hearing and sight, and he can see for a hundred leagues in the day or night. He also possesses a horn called Gjallarhorn, which he will blow at the onset of Ragnarök, the final battle of the gods.

The Bifröst is a bridge that spans the gap between the worlds, and it is made of fire, water and air. The bridge is constantly under attack by the forces of chaos, such as the fire giants and the Midgard serpent. The gods have to reinforce it with magic and runes, and they also have to pay a toll to the guardian of the bridge, Mimir, who is a wise being that knows many secrets. The Bifröst is also said to be very fragile, and it will break when the sons of Muspell, the fire demons, cross it during Ragnarök.

second interpretation 

Heimdall is a god in Norse mythology who guards the rainbow bridge Bifröst that connects Asgard, the realm of the gods, with Midgard, the realm of humans. He is the son of Odin and nine sea maidens, and he has extraordinary senses of sight and hearing. He can see for hundreds of miles, even at night, and he can hear the grass growing on the earth. Heimdall has two main weapons: a sword called Hǫfuð (meaning \"head\") and a horn called Gjallarhorn (meaning \"resounding horn\"). The sword is said to be his head, but the meaning of this is unclear. Some scholars suggest that it may refer to his wisdom or his role as a judge. The horn is a powerful instrument that he uses to alert the gods of any danger or invasion. He keeps it at the Well of Mimir, where he drinks from the water of wisdom. When he blows the horn, it can be heard in all nine worlds, and it signals the start of Ragnarök, the final battle between the gods and the giants. Heimdall is also known as Rig, Hallinskiði, Gullintanni, and Vindlér or Vindhlér, which have various meanings and interpretations. He is sometimes associated with light, fire, dawn, and social order. He is the originator of the three classes of humans: thralls, freemen, and nobles. He is also the enemy of Loki, the trickster god, and they are destined to kill each other at Ragnarök.

The sound of Heimdal's horn is a sign that Ragnarök, the end of the world, is coming. I wonder if there is a connection with the Christian idea of a trumpet that will announce the final judgment. Could it be that both religions are talking about the same event, and that their gods and followers will clash in a huge war? It's an interesting thought, but I don't know if there is any evidence for it.

first findings:
Heimdal, also spelled Heimdall, is a god in Norse mythology who guards the rainbow bridge Bifröst that connects Asgard, the world of the gods, and Midgard, the world of humans. He is the son of nine mothers, who are sisters and daughters of the sea god Aegir. According to one legend, Heimdal was born at the edge of the world, where the sky and the sea meet. He grew up with his nine mothers, who gave him gifts of strength, wisdom, and sight. He could see for a hundred miles in the day and night, and he could hear the grass growing on the earth and the wool on the sheep. He also had a horn called Gjallarhorn, which he would blow to warn the gods of any danger or attack.

here is the second finding:

Heimdal  is the son of nine sisters who are giantesses of the sea. According to some sources, his nine mothers are Gjolp, Greip, Eistla, Eyrgjafa, Ulfrun, Angeyja, Imth, Atla, and Jarnsaxa . Other sources give different names for his mothers, such as Atla, Augeria, Aurgiafa, Egia, Gjalp, Greip, Jernsaxa, Sindur and Ulfrun . Being born of nine mothers implies that Heimdal has a special connection to the sea and its waves . He is also endowed with great might and wisdom, and can see and hear everything that happens in the nine worlds. He needs less sleep than a bird and can see for a hundred leagues in the dark. He also has a horn called Gjallarhorn that he will blow at the onset of Ragnarok, the final battle of the gods .