... though it does have rhythm. (Para. 2)
Meaning: ... though it really has rhythm.
rhythm: n. regular repeated pattern of sounds or movements
That music has a strong rhythm. 这音乐的节奏很强。
Here "does" is used for emphasis (强调) and should be followed by the bare infinitive form of the verb.
He does have a brother in England. 他的确有个弟弟在英国。