A Split Pot occurs when two or more players share the same winning hand in the same pot.

Note: it doesn't mean these players necessarily have the exact same cards though.

Players could share the same board cards in addition to (or as opposed to) what they actually hold in their hand. A Split Pot is determined by five cards and there is no rank of suits. Most of the time, it will be determined by whoever has the highest ranked card. If you have the same five-card hand even after this, the pot will be split evenly among all winning players.
In the case that one or more players go All In, there's the possibility of creating a Side Pot(s).

Additional Side Pots allow for players in the hand to continue playing, with each additional pot going to the player with the best hand. Therefore, it's possible that a player with a worse hand may win the biggest Side Pot, while the player with the best hand wins a smaller Side Pot for which they went All In.

More info: