Learn Portuguese (Portugal): Nós começamos a frequentar o curso hoje. - We are starting to attend the course today.

In Portuguese, the verb começar (to begin/start) needs the preposition a when it is followed by another verb in its infinitive (dictionary) form. This structure, começar a + infinitive, is the standard way to say "to start doing something".

Is começamos in the present or the past tense here?

It is in the present tense! In European Portuguese, an acute accent is added to show the past tense for "we" form verbs ending in -ar. The present tense is começamos (we start), while the past tense is começámos (we started).

Does frequentar mean "frequently"?

Not quite! Frequentar is a verb that means "to attend" (like a course, school, or class) or "to regularly go to" a place. The word for "frequently" is the adverb frequentemente.

The English translation says "are starting". Could I say "estamos a começar" instead?

You could, as estar a + infinitive expresses an ongoing action (we are starting). However, Portuguese very often uses the simple present tense (começamos) for actions happening today or in the near future, making this sentence sound perfectly natural as it is.