It's used to talk about things which might happen in the future. Of course, we can't know what will happen in the future, but this describes possible things, which could easily come true.
Action + future result
if + present simple + will/won't + infinitive
If it rains, I won't go to the park.
If I study today, I'll go to the party tonight.
If I have enough money, I'll buy some new shoes.
If she doesn't leave soon, she'll miss the bus
Lesduur is: 40 min
