1001 B
It will happen, if
This means that what Yahweh promises will happen if the Israelites obey his commands.
that I command
Here "I" refers to Moses.
with all your heart and with all your soul
The idiom "with all your heart" means "completely" and "with ... soul" means "with all your being." These two phrases have similar meanings. See how you translated this in Deuteronomy 4:29. AT: "with all your being" or "with all your energy" (See: rc://en/ta/man/translate/figs-idiom and rc://en/ta/man/translate/figs-doublet)
I will give the rain of your land in its season
"I will cause it to rain on your land in the proper season"
I will give
Here "I" refers to Yahweh. This can be stated in the third person. AT: "Yahweh will give" or "He will give"
the former rain and the latter rain
This refers to rain at the beginning of the sowing season and rain for maturing the crops for harvest. AT: "the autumn rain and spring rain" or "the rain in the right seasons"