Characters
Your sentence
他 是 我 最好 的 朋友
Words in this sentence
他
(third-person singular) (since the early 20th century, usu. male) he; him; his; (bound form) other; another; some other (as in 他日 (tārì) and 他人 (tārén))
是
to be (followed by substantives only); correct; right; true; (respectful acknowledgement of a command) very well; (adverb for emphatic assertion)
我
I; me; my
最好
best; had better ...; it would be best to ...
的
of; ~'s (possessive particle); (used after an attribute when it modifies a noun); (used at the end of a declarative sentence for emphasis); (used after a noun, verb or adjective to form a nominal expression, as in 皮革的 (pígéde) "one made of leather" or 跑堂儿的 (pǎotángrde) "a waiter (literally, one who runs back and forth in a restaurant)" or 新的 (xīnde) "new one"); also pr. dì or di in poetry and songs
Particle
朋友
friend