@anno - the comma in your sentence serves as the "and". If you remove it, then the sentence sounds as weird as the one without "and". Also, your first variant did include the "and". By the way, this sentence explains a lot about how Arabic grammar works. The implied "to be"; as well as how adjectives work, their placement, and the nesting of more than one adjectives. But I agree with your point that there are a few different ways how this can be said in English.
I beg to differ. This is not a translation class but language learning class. So the given answer (read "translation") is perfectly fine as well as grammatically correct (reasonably).
Another grammatically correct "translation" could be "We park our car in a big and cold area".
Or "The garage is not small and warm".
Or "The temperature within the large car-holding shed is low at the moment".
All grammatically correct. But don't help us learn Arabic, which is the point of this lesson. So I will stick to "The garage is a big and cold garage" if you don't mind.
The space was just in my typing here with the quotation marks. There was no space when i answered and it wasn't accepted
What is weird, and what do you propose instead?
The above answer is grammatically "A is a B and C D". Where A & D are nouns, and B & C are adjectives.
In the current sentence
A = The garage; B = big; C = cold; D = garage.
Try it with
A = Cycling; B = nice; C = easy; D = exercise.
Does it still sound weird to you?