It means just right at two o'clock.Not a Minute More,Not a Minute Less.

点整 = 点钟

点整isn't a singel word.两点整have the same meaning as两点。but if we want to say two o'clock(a correct time),we usually use 两点整。if we just want to say (time)aroud two,just say 两点is ok.

zero mins to 2, zero mins past 2, it's the very 2 o'clock

two o'clock sharp