Learn Finnish: Minä autan ystävää.

The verb auttaa (to help) is a partitive verb. In Finnish, certain verbs always require the object (the person or thing receiving the action) to be in the partitive case. Because you are helping a friend, the basic word ystävä must become ystävää.

The dictionary form for "to help" is auttaa. Why does it only have one 't' in autan?

This happens because of consonant gradation. When you add the -n ending to say "I do", it closes the final syllable of the word. This makes the strong double consonant tt weaken into a single t.

Why are there two 'ä's at the end of ystävää?

The dictionary form of the word is ystävä. To make it partitive, we need to add the partitive ending, which is either -a or -ä. Because of vowel harmony, words that already have front vowels like ä or y take the -ä ending. Adding this to the end of ystävä gives us the double vowel in ystävää.

Does Minä autan mean "I help" or "I am helping"?

It means both! Finnish does not have a separate continuous tense like English does with "am helping". You can translate Minä autan as either "I help" or "I am helping" depending entirely on the context.