Learn Polish: Wczoraj spotkałem starego kolegę. - Yesterday I ran into an old friend.

Although kolega is a masculine word (referring to a male friend), it ends in -a. In Polish, masculine nouns ending in -a follow the feminine noun rules in the singular. To make it the direct object (accusative case) for the verb spotkałem, you change the -a to -ę, just like you would for a feminine word.

If kolegę uses a feminine noun ending here, why is the adjective starego in the masculine form?

This is a classic Polish grammar trap! Even though the noun kolega borrows feminine endings, it is still logically a masculine person. Adjectives must always match the noun's true gender. For a masculine person in the accusative case, the adjective ending is -ego, which gives us starego (instead of the feminine starą).

How can we tell the gender of the person speaking in this sentence?

The verb spotkałem gives it away. In the Polish past tense, the ending tells you the gender of the speaker. The -łem ending means "I (a male)" did the action. If a woman were saying this sentence, she would say spotkałam.

Why use the perfective verb spotkałem instead of the imperfective spotykałem?