Learn Turkish: Bu belgeyi kalemle doldurabilir miyim? - Can I fill out this document with a pen?

It combines several parts: the verb root doldur- (to fill), the ability suffix -abil (can), the aorist tense suffix -ir, and the question particle for 'I', which is miyim. When asking for permission ('Can I...?'), Turkish uses this combination of the ability suffix, aorist tense, and the question particle.

Why is there a -yi at the end of belgeyi?

belge means 'document'. The -i is the specific direct object (accusative) ending, with a y as a buffer letter to separate two vowels. Because the sentence says bu belge (this document), it points to a specific item receiving the action of the verb, so it requires this ending.

Does the -le in kalemle mean 'with'?

Yes! It is the shortened suffix form of the word ile, meaning 'with' or 'by means of'. Since kalem ends in a consonant and its last vowel is an 'e', it takes the -le suffix. If you wanted to say 'with a phone', it would be telefonla (using the -la version for back vowels).

Can I use doldurmak for physically filling something, like a glass, or is it only for documents?

You can use it for both! doldurmak literally means 'to fill' or 'to make full'. It is widely used for filling out forms and documents, as well as physically filling a glass with water or a bag with groceries.