"Shadi has a big garage."
Translation:عِنْد شادي كَراج كَبير.
In correct Arabic use عندي means 'I have with me now'. To say you HAVE something, in the sense of 'it is my property', you say لي or لديّ. In dialect Arabic there may be no difference, but in MSA you are stating that you have put your garage in your pocket.
That's like a repair shop, correct? That's one common meaning of "garage" in English. But "garage" probably more often means an enclosed space for parking a motor vehicle or vehicles, often part of a house.