I think you answered your own question...'no' means nothing to him, because nobody has told him what it means. You can tell a toddler 'no' until you are blue in the face and it means zip. My therapist, indicated to us that kids need to have reasoning taught to them, and that things like 'no' really require a sense of what is right and wrong...toddlers just don't have that ability yet.
Here's what I've done in my preschool class and at home with my 2.5 year old little monkey...
If he is doing something dangerous, attempt to re-direct with explaination. My son became a huge fan of throwing blocks at the cat, she would move and he would throw. It was not cute or funny, but I did this...'J do not throw blocks at the cat, you could hurt her. Let's use the blocks like this.' -- then, I would sit down and show him how to use them.
If that didn't work, I worked my way up to the if you can't use your toys like Mommy showed you then Mommy will put it away in the closet for ten minutes. Set the egg timer, and usually got met with a tantrum...of enormous proportions. I would then, proceed to sit with my son and explain what he had done wrong. That it was okay to be frustrated, mad, sad...whatever, but if he can't use his toys properly then he wasn't going to be able to play with them. In essence, a 'toy timeout'.
Over a period of about two to four months, it sunk in...now, if he does something wrong I still explain and when he knows he's done something wrong he'll even walk the toy to the closet himself.
Toddlers lack impulse control, and yours is no different. He is exploring his world and trying 'new' things out...like biting the cord of the vaccum. But, he has no idea why you're telling him 'no' or yanking his arm or changing the tone of your voice. Your little one is not just trying to get a reaction out of you, but trying to figure out his world. Now, he just needs a little guidance from Mom about how to deal with his world and what is 'right and wrong'.
He's only 14 months old, and needs you to show him these things. Kids to automatically know how to behave or how to be good...