Translation:I do not understand the necessity for these checks.
My native language is English. We would much more likely say "the necessity FOR" (not "of"). The word "checks" would be very unnatural, at least in the USA. I think what they may be trying to say is "I don't understand the necessity for these inspections" (or somewhat less formally, "I don't understand why these inspections are necessary")
Hmmmm... is English your mother tongue? I cannot help with English prepositions, I mess up with them as well.