Learn Finnish: Keneltä sinä saat rahaa? - Who do you get money from?

Keneltä is formed from the question word kuka (who) plus the ablative ending -ltä (from). In Finnish, when you receive something from a person, you use this 'from someone' ending.

Why do we use an ending on 'who' instead of a separate word for 'from'?

Finnish rarely uses separate small words (prepositions) like English does. Instead, it adds case endings directly to words to show direction or location. The -lta/-ltä ending attached to the word for 'who' does the exact same job as the English word 'from'.

Why is 'raha' (money) written as 'rahaa' in this sentence?

Rahaa is in the partitive case. Because money is an uncountable mass noun, you use the partitive case to show you are getting an unspecified amount of it ('some money'), rather than 'the money' in its entirety.

Could I leave out the word 'sinä' (you)?

Yes, you can! Because the verb saat (you get) already has the -t ending that specifically means 'you', the word sinä is optional. You will often hear people just say Keneltä saat rahaa? in everyday speech.