Learn Spanish (Latin America): Mezcla el huevo y hornea el pastel.

These are informal tú commands. For regular verbs, the affirmative tú command looks exactly like the he/she/it form of the present tense. Since mezclar and hornear are -ar verbs, you use the -a ending instead of the -as ending you normally use for tú.

Wait, doesn't mezcla also mean 'he or she mixes'? How do I know it's a command?

You are exactly right! Mezcla can mean 'he/she/it mixes' or it can be the command 'mix!'. You can tell which one it is from the context. Because this sentence gives a list of direct instructions, similar to a recipe, it's clear that it is commanding someone to do the action.

How do I pronounce the 'h' in huevo and hornea?

You don't! The letter 'h' is always silent in Spanish. You just start pronouncing the word from the first vowel. So, huevo sounds like WEH-vo, and hornea sounds like or-NEH-ah.

I learned that cake is torta. Can I use that instead of pastel?