If means if.
Source: Mencius Gongsun Chou Shang
Whoever has four ends in me, knowledge is expanded and filled. If the fire began, the spring began to reach. If you can fill, enough to secure the four seas; If it is not enough, it is not enough for parents.
Here is the translation:
Whoever has these four beginnings in himself knows how to enlarge them and enrich them, just as a fire has just started and a spring has just sprung up; if he can enlarge them, it is enough to stabilize the world. If you don't expand them, you can't even serve your parents.
\"If\" here means \"if\".