The document explains the first conditional, which is used to talk about possible situations in the present or future. It provides examples of conditional sentences using the structure of "if + present tense verb" in the condition part and "will + base verb" in the result part. Some examples given are "If it's sunny, we'll go to the park" and "If you study hard, you will pass the test." The document also provides exercises for learners to practice forming first conditional sentences.