It's primarily a skill game, although luck plays a huge role. In any single given hand, luck is the predominant factor in who will win or lose. However, poker players don't play a single hand. They play hand after hand after hand & and overall, skill dominates.

If you are looking for free Texas Holdem practice, the WSOP Poker app is one of the best ones out there. US players are allowed to play here and the free apps for iOS and Android are both equally amazing. WSOP Poker, however, is a free-to-play platform you can't use for anything more than free poker practice.