Suppose you have the statement “if P, then Q.”
This can also be read as “P is a sufficient condition for Q.”
That is to say, P is a sufficient, but not necessary, condition for Q. The not necessary part is important, because it means that even if P were false, we may still be able to satisfy Q.
Let’s say P is the statement “I go to school,” and Q is “I have books.” So “if P, then Q,” is “if I go to school, then I have books.” While it may be true that me going to school means I have books, it could also be that I have books, but I don’t go to school (in which case, the statement is still true, even if P is false).