Learn Icelandic: Kann hann að tefla? - Does he know how to play chess?

When the verb kunna means 'to know how to do something', it must be followed by að and the infinitive of the action verb. So 'knows how to play' is kann að tefla. This is a special rule for kunna.

What is the exact difference between asking Kann hann að tefla? and Getur hann teflt?

The verb kunna is about having the learned skill or knowledge. So, Kann hann að tefla? asks if he knows the rules of chess. If you use geta (to be able to), you are asking about physical ability or opportunity at this moment, like asking if he is available to play chess right now. Also notice that geta doesn't use að and requires a different verb form!

Wait, is there a single verb just for playing chess?

Yes! While English uses the verb 'play' and the noun 'chess', Icelandic has the specific verb tefla which simply means to play chess. You don't use the regular word for playing games (spila).

Why is the form kann instead of a regular conjugation like kannar?