It means "...that means a lot to me".
Many kisses for you my love.
If it's a question, it means, "What mean everything to my dad?" If it's a sentence fragment, it could mean, "...that mean everything to my dad."
ustedes significan todo para mi ustedes son mi mundo
I have waited a long time for this
"You are everything to me" in Spanish is "Eres todo (or "toda" if you are speaking to a female) a mí". It is pronounced "AIR-ace TOE-doe ah me". Please see this site for confirmation of the translation: http://www.answers.com/library/Translations
You study a lot for your favorite class.
Literally translates to: "I have a lot of love for you, always."
They study a lot for science class.
It helped me a lot because now I'm in the best math group.
helped a lot because now I'm in better group for mathematics
for
"Soy para ti" translates to "I am for you" in English.