。
He's very sexy.
Literal
He [topic-は] very sexy [copula-だ].
セクシー is the katakana loanword from English 'sexy,' used as a na-adjective: セクシーだ, セクシーな人. Loanwords ending in vowels typically behave as na-adjectives. Worth noting that this English loanword feels less crude/informal in Japanese than its English original — it's a fairly neutral compliment.