Learn Icelandic: Við göngum beint áfram.

This happens because of a very common Icelandic vowel change called the U-shift. When a root word has an a, and the ending has a u (like the -um ending for the 'we' form), the a changes to an ö. So, gang- + -um becomes göngum.

Why does the word beint end in a -t?

In this sentence, beint is used as an adverb meaning 'straight'. To make an adverb out of an adjective in Icelandic, you usually just take the neuter singular form of that adjective. The base adjective for 'straight' is beinn, and its neuter form is beint.

Does áfram mean the exact same thing as fram?

They are related, but áfram specifically means 'onward' or continuing in a current direction. Fram generally just means 'forward'. When giving or following directions to keep moving straight ahead, beint áfram is the set phrase you will always use.

Does Við göngum mean 'We walk' or 'We are walking'?

It can mean both! Icelandic does not have a separate present continuous tense (like the English '-ing' form) for standard action verbs. Depending on the context, Við göngum translates perfectly to either 'We walk' or 'We are walking'.