4th and long is a phrase in football used by players, coaches and fans to explain a certain situation before the 4th down takes place. In football, each team has four opportunities, also known as downs, to move the ball ten yards down the field. Depending on how the team does, by the fourth down, they may have to still cover a lot of distance. The phrase 4th and long comes into play when it's the 4th down and the team has more than 5 yards to go with only one try left- which is definitely a challenging feat.
If the team chooses to play, many quarterbacks look for long passes when it's a 4th and long situation. Any pass down field is promising for these situations because the team is more likely to get another set of downs the longer the pass. Quarterbacks also sometimes run the ball the remaining yards. Since this is their last chance at maintaining possession, if the quarterback sees an open lane, he can also run the ball.
If the team feels that they are close enough to the goal, they can opt to kick a field goal. Although this is fewer points than a touchdown, it can be a safe bet. The offensive team can also perform a punt, which clears the ball down the field to the other team, in hopes to get them as far away from scoring a touchdown as possible. The goal is to then tackle the player who received the punt and keep them away from the end zone.