Does a flush beat a straight?

Yes. Flushes are less common than straights, so they rank higher.

Can a flush have five cards of different suits?

No. All five must share one suit. Colours do not matter, only the suit.

Rank 5 of 10

Flush

Any five cards of the same suit, not in sequence.

Chance in Hold'em (7 cards): 3.03%
Odds against: 32.1 to 1
Chance in 5 cards: 0.1965%
Five-card combinations: 5,108

Flushes are compared card by card from the highest down. An Ace-high flush beats a King-high flush. If the top cards match, compare the second card, and so on.

With four of one suit on the board, anyone holding a single card of that suit has a flush, so the highest card of the suit wins. The Ace-high flush is "the nuts".

Beats: Straight and everything below.

Questions players ask

Does a flush beat a straight?: Yes. Flushes are less common than straights, so they rank higher.
Can a flush have five cards of different suits?: No. All five must share one suit. Colours do not matter, only the suit.