Learn Polish: Jadę do pracy autobusem. - I am going to work by bus.

In Polish, you must use a different verb depending on whether you are walking or taking a vehicle. Because you are traveling by bus, you use jadę (from the verb jechać, meaning to go by a vehicle). If you were walking to work, you would use idę (from iść, meaning to go on foot).

Why is it do pracy and not just do praca?

The dictionary word for work is praca, but the preposition do (meaning "to") always requires the noun following it to take the Genitive case. For feminine nouns ending in -a like praca, the ending changes to -y, making it pracy.

Why does autobus change to autobusem, and where is the Polish word for "by"?

Polish doesn't use a separate word like "by" for transportation. Instead, it uses the Instrumental case to show the means or tool you are using to do something. For a masculine noun like autobus, you just add the ending -em to make it autobusem, which means by bus.

Could I change the word order and say Jadę autobusem do pracy instead?

Yes! Polish word order is very flexible. Putting autobusem at the end of the sentence places a slight emphasis on the fact that you are taking the bus rather than a car or tram. However, both versions are perfectly natural and mean exactly the same thing.