The correct answer is 12.

Please Note:
Sides are the straight lines that make a plane shape.

See example:

Solution:

Consider the hexagon table below:

A hexagon has 6 sides.

So, 1 hexagonal table has 6 sides.

Each side of the table is for 1 person.

So, 6 persons sit on one such a table.

Regina has 2 of these hexagonal tables.

That is, 2 tables × 6 persons = 12 persons.

So, Regina can have 12  persons over for dinner.