Often translated "the Almighty," this is perhaps better understood as "[God of the] Mountain"
Hebrew "he, he will deliver" is perhaps emphatic, "He will certainly deliver"
That is, a small, round shield, or perhaps a surrounding bulwark
This is the most straightforward translation of the Hebrew, though the "you" of each line would refer to a different person. A more unusual rendering would be "Because Yahweh, my refuge, even the Most High, you have made your dwelling place ..."
The sense is that of making something inaccessibly high, like a fortress