Learn German: Der Kollege ist krank. Es tut mir leid. - The colleague is ill. I am sorry.

Germans do not use the verb "to be" to express being sorry. The fixed phrase Es tut mir leid literally translates to "It does to me sorrow." It is the standard way to apologize or express sympathy in German.

What does the word mir mean in this phrase?

mir means "to me". It is a form of ich (I) used when an action happens indirectly to you (known as the dative case). In this expression, the sad situation is doing sorrow to you.

Why is leid written with a lowercase letter?

In German, all nouns are capitalized. While das Leid (the sorrow) can be a noun, in the fixed phrase leidtun (to be sorry), leid is treated as part of the verb. Therefore, it is written in lowercase.

Does der Kollege refer to any coworker, or specifically a man?

Der Kollege specifically means a male coworker. If the colleague were a woman, you would use the feminine form, die Kollegin.