Learn Portuguese (Portugal): Eu juro que farei tudo pela nação. - I swear that I will do everything for the nation.

In this sentence, farei is the 'eu' (I) form of the future tense for fazer (to do/make). Instead of adding the ending to the full infinitive (which would incorrectly be 'fazerei'), fazer uses the irregular stem far-. Then you just add the regular future ending for 'eu', which is -ei, giving us farei.

Could I say vou fazer instead of farei?

Yes! In everyday spoken Portuguese, it is much more common to use vou fazer (I am going to do) rather than the simple future tense farei. However, farei sounds more formal, dramatic, or solemn, which perfectly fits a strong statement like swearing an oath to the nation.

Why does the sentence use pela instead of para a for 'for the'?

We use pela (a contraction of por + a) because here 'for' means 'on behalf of' or 'for the sake of' the nation. While para is generally used for a physical destination or a specific recipient, por is used when expressing a cause, a motive, or doing something on behalf of something else.

Is tudo related to todo?