Can someone answer some technical questions about Cable TV?

Lake Grove NY

Description

Thanks for reading! I know these might be Cable 101 questions but I know nothing about cable TV. Maybe you can answer them for me? Please keep it simple in your response! I have 1 line of coaxial cable coming INTO my apt but would like to set up 2 TVs. Are there different "qualities or grades" of coaxial cable with some types transmitting/working better than others as far as clarity/quality on the TVs? If so what are they? Are some 'Brands' better than others? I also have a 'splitter' whoa I know... I'm getting crazy technical! I'm posting a photo of the one I have. The one I have is a 1 to 3 but I only need a 1 to 2. I can use just 2 of the openings and leave the 3rd empty, right? Is this one what I need? Or is it a really junkie one and I would be better off buying a new one? Thanks so much for your help! It is greatly appreciated!!!