Moses continues to speak to the people of Israel. He speaks as though they were one man, so all instances of "you" and "your" are singular. (See: [[rc://en/ta/man/jit/figs-you]])
Here "heart" and "soul" are metonyms for a person's inner being. These two phrases are used together to mean "completely" or "earnestly." (See: [[rc://en/ta/man/jit/figs-metonymy]] and [[rc://en/ta/man/jit/figs-doublet]])