Do you have a table for two?
TAH-vo-lo — three syllables, stress on the first.
When you walk into a restaurant without a reservation and want to know if there is space.
'Avete' is the second person plural of 'avere' (to have), used to address a business or group of staff. 'Per due' literally means 'for two'. You can swap 'due' for any number: per tre, per quattro.
C'è un tavolo libero per tre?
Is there a free table for three?
'Libero' (free/available) makes the request slightly more specific
Siamo in quattro — avete posto?
There are four of us — do you have space?
Very natural spoken version, slightly informal
Possiamo sederci?
Can we sit down?
Even shorter — fine in casual trattorias
In Italy it is very common to eat late — dinner rarely starts before 8 pm. Arriving at 7 pm you will often find the restaurant empty or even not yet open.