Yes, it can be confusing.
Basically, a gerund is a verb form ending in 'ing' that is used like a noun. So for example:
Swimming is great!
She enjoys swimming.
In these sentences 'Swimming' is a gerund - if we replace it with a noun such as 'Ice cream' we get correct sentences.
Ice cream is great!
She enjoys ice cream.
So as you can see in these sentences 'Swimming' is used just like a noun.
You may also notice that in the above sentences there is no verb 'be' in front of the word 'Swimming' if this were a progressive/continuous verb there would be. The above sentences are all in the present simple.
Let's look at a different sentence.
Peter is swimming in the pool.
When we try to replace this with a noun such as ice cream we get -
*/Peter ice cream in the pool./*
or if we leave the verb 'is' in the sentence we get -
*/Peter is ice cream in the pool./*
Neither of these make sense because here 'swimming' is a progressive/continuous verb and the sentence 'Peter is swimming in the pool.' is in the present continuous.