Learn French: Cette pêche est très sucrée.

Sucrée is an adjective describing pêche (peach). Since pêche is a feminine noun, the base adjective sucré (sweet) needs an extra e to agree with it.

Does pêche always mean "peach"?

No, la pêche is also the word for "fishing". Context usually makes it obvious! There is also a very common informal expression, avoir la pêche, which means "to be full of energy" or "to feel great".

Why use Cette instead of Ce for "this"?

Cette is the feminine singular form of the demonstrative adjective ("this" or "that"). Because pêche is feminine, we use Cette. Ce is used for masculine nouns, and Cet is used for masculine nouns starting with a vowel sound.

Can I use sucrée to say a person is "sweet"?

No, sucré strictly means sweet in taste, containing sugar. If you want to say a person or a gesture is "sweet", you should use words like gentil (kind), adorable (adorable), or mignon (cute).