Learn Polish: Mam jedynkę i dwójkę. - I have a one and a two.

The regular numbers jeden and dwa are adjectives or numerals used to count items, like one dog or two books. The words in this sentence come from the feminine nouns jedynka and dwójka. These are used when the number itself is the object you are talking about, rather than a quantity.

Why do both of these words end in -ę here?

The verb mam (I have) requires its direct object to be in the Accusative case. Because the base dictionary words jedynka and dwójka are regular feminine nouns ending in -a, they follow the standard rule and change their endings to -ę.

In what real-life contexts would a Polish speaker actually say this sentence?

You would use this when talking about everyday things that are simply named by their numbers. The most common examples are discussing school grades you received (a 1 is a failing grade in Poland, and a 2 is barely passing), listing the bus lines that stop near your house, or talking about game pieces.

Can dwójka also be used to talk about people?

Yes! Dwójka can act as a collective noun meaning a group of two, especially for children or mixed-gender groups (for example, dwójka dzieci means two children). However, in this exact sentence where the words stand completely alone, it is much more likely to refer to a grade or a bus line.