for / four 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. 👇
for: NA
four: (noun) the cardinal number that is the sum of three and one. (adjective) being one more than three.
for: f·AO·r
four: f·AO·r
(Examples are Wikipedia snippets under the CC ShareAlike 3.0 license. Definitions drawn from WordNet.)