Við erum til í að mála vegginn um helgina ef við finnum rétta málningu.

Vera til í is an idiomatic expression meaning to be up for, to be willing to, or to feel like doing something.

So:

• Við erum til í að mála... = We’re up for painting...
• Ég er til í það. = I’m up for that.

You should learn vera til í as a fixed phrase rather than trying to translate til and í separately here.

Here að is the infinitive marker, like English to in to paint.

The pattern is:

• vera til í að + infinitive

So:

• Við erum til í að mála = We are willing/up for to paint → natural English: We’re up for painting

Because the subject is við = we, and erum is the 1st person plural form of vera (to be).

Present tense of vera:

• ég er = I am
• þú ert = you are
• hann/hún/það er = he/she/it is
• við erum = we are
• þið eruð = you are
• þeir/þær/þau eru = they are

So við erum is the correct match.

Because vegginn is the definite accusative singular form of veggur (wall).

Here vegginn is the direct object of mála (to paint), so it appears in the accusative case:

• nominative: veggur = a wall
• accusative: vegg = a wall
• accusative definite: vegginn = the wall

The ending -inn is the suffixed definite article, so vegginn means the wall.

It is accusative singular feminine.

Why:

• málning (paint, the substance) is a feminine noun
• finna (to find) takes a direct object in the accusative
• the adjective rétta (right/correct) has to agree with málningu in gender, number, and case

So:

• rétta málningu = the right paint / correct paint

Because the adjective has to agree with málningu.

Here:

• málningu is feminine
• singular
• accusative

So the adjective réttur changes form to rétta.

This kind of adjective agreement is very important in Icelandic.

Um helgina means over the weekend or during the weekend.

In time expressions, um + accusative often means during or around a period of time.

Examples:

• um daginn = the other day
• um helgina = over the weekend
• um sumarið = during the summer

So this is a very natural time phrase in Icelandic.

Because Icelandic often uses the present tense to talk about future actions when the context makes the future meaning clear.

So:

• Við erum til í að mála vegginn um helgina...

is present in form, but naturally understood as a future plan:

• We’re up for painting the wall this weekend...

The same thing happens with finnum:

• ef við finnum = if we find / if we can find

Finnum is the 1st person plural present of finna (to find).

So:

• ég finn = I find
• við finnum = we find

In this sentence, finna can mean either:

• find in the literal sense, or
• manage to get hold of / locate

So ef við finnum rétta málningu can mean:

• if we find the right paint
• if we can get the right paint

Because after ef (if), Icelandic normally uses regular subordinate-clause word order, where the subject comes before the verb.

So:

• ef við finnum... = if we find...

This is different from some main-clause patterns in Icelandic, where the verb often comes in second position.

Yes. They are closely related:

• að mála = to paint (verb)
• málning = paint (the substance, noun)

So in this sentence you get both:

• að mála vegginn = to paint the wall
• rétta málningu = the right paint

This is a useful pair to learn together.

Yes. Because of the suffixed definite article -inn, vegginn means the wall, not just a wall.

That usually implies a specific wall already known from the situation or conversation.

Compare:

• mála vegg = paint a wall
• mála vegginn = paint the wall

No. It can also be used with nouns or pronouns.

Examples:

• Ég er til í kaffi. = I’m up for coffee.
• Ertu til í það? = Are you up for that?
• Við erum til í að hjálpa. = We’re willing to help.

So with a verb, the pattern is:

• vera til í að + infinitive

With a thing or idea, you can simply use:

• vera til í + noun/pronoun