Ah, the good old English gerund! Honestly, most native speakers aren't even taught this; they just do it automatically. But anyway, there are two main uses of the gerund that come to mind. First, the gerund is used in what is called the "present progressive tense". This is formed by using a conjugated form of "to be" and the gerund. Examples: I am talking. You are eating. She is watching a movie. Bob was going to a restaurant. The children were being naughty. The Present Progressive implies that something is happening at the very moment you're speaking. (It may actually have a different name in the past tense. To any grammar people, feel free to correct me there). It's quite common in English. The other main use of the gerund is when you are using the verb as a noun. Many times, the infinitive can be used here as well. Examples: I like watching movies. Seeing is believing. Writing a novel is very difficult. As you can see, the gerund is being used as a noun. It's important to note that the infinitive and the gerund are not always interchangeable. "I want to eat popcorn" in fine; "I want eating popcorn." is not. Let me know if you have any followup questions! This is a pretty complex topic, so I'm sure to have made some mistakes!

gerund = отглагольное существительное

I think you might stump the English natives with this one. :D Speaking for myself, I have never even heard of this word. Maybe I'm just a dummy.