The document discusses conditional sentences that describe a condition and the resulting outcome. It provides examples of different types of conditional sentences, including: present conditional sentences with "if" indicating a possible present or future condition (e.g. "if you stand on the sun, you get hot"); past conditional sentences with "if" referring to an unlikely or counterfactual past situation (e.g. "if I hadn't been sick, I would have gone to her birthday"); and future conditional sentences using future tense verbs to talk about possible future conditions and results (e.g. "if you tell me, I will not tell anybody"). It also includes exercises for filling in the blanks of future conditional sentences.