Voting 'YEA' is a term used to express approval or agreement in a decision-making process. It is typically used in a voting system, where a person casts their vote in favor of a proposal or motion. The term 'YEA' is derived from the Old English word 'geeah', which means 'YES'. In the context of a crossword puzzle, the three letter solution PRO is an abbreviation for the word 'PROFESSIONAL', which can be used to describe someone who is experienced and knowledgeable in a particular field.