Learn Spanish (Latin America): ¡Tú sí que desenterraste un tesoro enorme!

The phrase sí que is used for strong emphatic affirmation, often to counter an expectation or show surprise. While realmente just means 'really,' sí que adds a conversational punch, similar to saying 'You sure did unearth a huge treasure!' in English.

Why is the subject pronoun Tú included here when it is normally dropped?

Adding the subject pronoun before sí que makes the statement even more emphatic. It singles the person out, giving the feeling of 'Wow, you of all people really found a treasure!' or 'You sure did find it!'

I recognize the middle part of desenterraste. Is it related to the word for earth?

Exactly! The verb desenterrar is built from the prefix des- (meaning to undo or remove) plus the root tierra (earth or dirt). So it literally translates to 'unearth' or 'dig up.' Notice how the 'ie' from tierra reduces to just 'e' in desenterraste because the spoken stress shifts to the verb ending.

Would it be wrong to put the adjective first and say un enorme tesoro?

It would not be wrong, but it changes the nuance. Placing enorme after the noun is the standard, objective way to say the physical size of the treasure is huge. Putting it before the noun makes it more poetic and subjective, emphasizing your personal awe at the discovery.