Learn Portuguese (Portugal): Eu aprendo português.

In Portuguese, the names of languages, nationalities, and months are not capitalized unless they appear at the very beginning of a sentence. So, while we write "Portuguese" in English, it is português in Portuguese.

Can I leave out the word Eu and just say Aprendo português?

Yes, you can! Because the verb ending in aprendo already tells us that the subject is "I", the pronoun Eu is often dropped in everyday conversation unless you want to add emphasis.

What is the dictionary form of aprendo?

The infinitive (dictionary form) is aprender (to learn). It is a regular -er verb, so to make it match Eu (I), you remove the -er and add -o, giving you aprendo.

How would I use the verb gostar from this lesson to say "I like to learn Portuguese"?

You would say Eu gosto de aprender português. Remember that gostar is always followed by the preposition de before the action you like doing.