Four downs are allowed to get 10 yards.
In the NFL, if the offense scores a touchdown, the team is credited with a first down. Check any NFL game's play-by-play on nfl.com and count all of the first downs. Now, compare them to the total first downs credited in the box score. If touchdowns were scored by the offense, they must be added to make the totals come out even.
In Canadian football, a team has only three downs to make a first down.
The offense gets 4 downs to travel ten yards. If they make the ten yards, they get 4 more downs. This continues until they either score a touch down or a field goal. If a team fails to make 10 yards within the 4 downs, they usually opt to punt the ball away on the 4th down so the opposing team starts their drive with poor field position.
In the NFL and most other American football rules a team gets four downs to either score with a touchdown, a field goal, or to make a first down, and start the count of downs again. Usually the fourth down is used to punt the ball away, rather than give the football up on the spot, if the previous three downs didn't result in some more favorable outcome.
Depends on how many yards they have to go?!?
It means that the team had the ball for three downs and failed to make a first down (10 yards) so they're going to have to kick the ball away on the fourth down.
You need to run the ball 10 yards in order to make a first down. If you fail to do this the downs fall to 2nd, 3rd, and 4th. The ball gets turned over after the 4th down if you failed to either punt the ball away or make a first down by then.
In Canadian football, a team has only three downs to make a first down. That's why Canadian football is a "wide open" game, unlike the more static game that's played in the US.