say / se are similar-sounding terms with different meanings (referred to as homophones). To better understand the differences, see below for definitions, pronunciation guides, and example sentences using each term. 👇
say: (noun) the chance to speak. (verb) communicate or express nonverbally. (verb) utter aloud. (verb) state as one's opinion or judgement; declare. (verb) recite or repeat a fixed text. (verb) indicate.
se: NA
say: s·EY
se: s·AW·th·IY·s·t
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)