。
I bought a red tie.
Literal
Red tie [object-を] bought-[polite-ました].
A textbook-level sentence. 赤い is a true i-adjective modifying ネクタイ directly (no な). ネクタイ is a katakana loanword from English 'necktie.' Subject omitted as usual. The sentence is a clean example of basic SOV structure with adjectival modification.