I've read on the Internet that the gerund is a form of the verb, which serves to indicate an action in the Present Perfect Tense in English and Spanish.
What is the real meaning of the gerund in English?
In our country, we're taught that the gerund is the mixture of a verb and a noun.
Is that right?
Gerunds function as nouns in sentences. So technically gerunds are nouns.
However, they can take subjects, objects, and complements like verbs. The term verbal is used to describe words like these that live in a little of both worlds. Infinitives and participles (I think) are other verbals.
Many people will say -ing words are verbs (and they aren't completely incorrect) but the only time they are part of a verb is when acting as a helping or auxillary verb with be or have.
I don't think it's correct to say any -ing word is a gerund either, because you can't know until you know what function it's serving in a sentence.
I've read on the Internet that the gerund is a form of the verb, which serves to indicate an action in the Present Perfect Tense in English and Spanish.
Consider this example:
I am walking to the store.
To be + {-ing} is how English expresses the present continuous (not perfect) tense, which is the normal present tense used to describe things happening now. -ing here is not a gerund. I believe it's technically an adverb, but it's easier if you just consider am walking to be a two-word verb.
Present perfect tense uses have in English:
I have walked to the store.
which AFAIK corresponds to haber + {past participle} in Spanish but you might want to check with https://spanish.stackexchange.com on that.
I did find this which seems to call any -ndo word in Spanish a gerund. If this is a common thing taught in your country I believe there will be a conflict with a lot of information around that makes the above distinctions. But I'm no expert on English educational literature or websites so I could be wrong. Hopefully the above helps, though.
Spanish I think will use the infinitive where a lot of times in English the -ing form of the word is used.
Walking helps me stay fit = Caminar ayuda a mantenerme en forma (from Google Translate)
In English, you could say this:
To walk helps me stay fit
but it sounds weird.
Your first sentence about the nature of a gerund is of very low quality, or rather it is simply wrong. The gerund is a verbform with the ending -ing, just as the present participle, and it has the nature of a verb and a noun.
The gerund has four forms, two active and two passive forms: doing, having done, being printed, having been printed.
The gerund has two difficulties, one being its double nature of having verbal and noun character, the second difficulty being that gerund and present participle have the same form.
