Translation:My grandchildren like to eat chocolate.
Surely. Netos is grandsons, but in a group (grandsons +granddaughters) we also say netos. Both work right since we dont know if they are just boys or boys and girls.
So how do you distinguish between netos to me grandchildren and netos to mean grandsons?
Could someone explain to me when we use 'comer'? It's never come up for me before now. :/
To add a little to what Paulenrique has said, the Portuguese infinitive is often used where we use the infinitive in English (i.e., the "to" form of the verb, such as "to run", "to eat" and "to be" and so on) although sometimes it can also make sense to translate it with the "-ing" form ("running", "eating" and "being").
One very common use of the Portuguese infinitive (particularly in speech) is to express the future; this is done using a conjugated version of "ir" ("to go") plus the infinitive so you can write "Eu vou comer" to mean "I am going to eat" or "I will eat".
You can occasionally find words that look exactly like the infinitive of the verb but in reality they are conjugated versions (of the future subjunctive of regular verbs).