An IPTV stream player is an Android app — installed from an APK file — that plays live-TV playlists such as M3U, M3U8, or Xtream Codes links on phones, Android TV boxes, and Firesticks. The thing worth understanding is that the player is just the player. You point it at a playlist URL your provider gives you, and it handles the channel list, the EPG guide, and the video decoding. The player is almost always free; the playlist is what you actually pay for. That split is the whole reason the search exists.
Setting one up is straightforward. You sideload the file because Android blocks installs from outside the Play Store by default, so you toggle "install unknown apps" for your file manager first, then open the app and paste in your M3U link. On a Firestick you'll want the Downloader app to fetch the file. The common failure points aren't the player — it's a dead playlist URL, a region lock that needs a VPN, or a box with too little RAM to hold 1080p without buffering.
I keep a shortlist of the ones that held up over a year of daily viewing, and I wrote up the setup for the one stream player APK I actually run day to day, including the M3U versus Xtream tradeoff. Worth reading before you pick one blind.