Mummo ja vaari istuvat keittiössä juomassa kahvia.

and

Breakdown of Mummo ja vaari istuvat keittiössä juomassa kahvia.

• kahvi: the coffee
• juoda: to drink
• -ssa: in

Questions & Answers about Mummo ja vaari istuvat keittiössä juomassa kahvia.

What do mummo and vaari mean, and are they the normal words for "grandmother" and "grandfather"?

Mummo means grandma / granny, and vaari means grandpa / grandad.

They are:

• informal, warm, everyday words, often used about or to your grandparents.
• similar in tone to "gran" / "granny" / "grandma" and "grandpa" / "granddad" in English.

The more neutral or formal words are:

• isoäiti = grandmother
• isoisä = grandfather

So you could also say:

• Isoäiti ja isoisä istuvat keittiössä juomassa kahvia.
  That would sound a bit more formal or neutral; mummo ja vaari is homely and affectionate.

Why is the verb istuvat used, and how is it formed?

The base verb is istua = to sit.

Istuvat is:

• present tense
• 3rd person plural (they)

Formation:

• stem: istu-
• personal ending for they: -vat (or -vät depending on vowel harmony)
  → istu-
  • -vat = istuvat = they sit / they are sitting

Finnish has no separate continuous tense, so istuvat can mean both:

• (habitual / repeated)