Pl0x is a leet term, meaning "please". Plz is another word meaning "please", which appear just about as often.
Pl0x used in a sentence:
Isaac, will you let me cheat off you in latin pl0x?
pl0x is a term usually used at the end of a sentence.
S0ldi3r fr0nt pl0x KostA+ pr0 pl0x t3h l33t sht