“No offense, but I just don't see what the point of those is.”

You see that your friend has a tablet computer. You don't like tablet computers because you don't think that they're useful for anything. You want to tell your friend your opinion, but you know that it might annoy him for you to criticize his device. You say:

No offense, but I just don't see what the point of those is.

No offense, but...

This is a way to introduce an opinion or fact that you think might make your listeners angry. 

To "offend" someone means to say something that makes them angry at you. Here are some examples of things that you could say which would offend people:

• telling someone that they're fat
• talking about racial stereotypes
• expressing your negative opinions of women
• criticizing someone's idea in a meeting

If you have something like this which you know is going to offend people, but you want to say it anyway, it's common to introduce your sentence with "No offense, but..."

I don't see the point of (something)

This is a phrase that people say when they don't think that something is useful or necessary.

I don't see the point of voting; all politicians are more or less the same anyway.

I've never seen the point of making up my bed, when I'm just going to mess it up again the next night.

"The point" of something is the reason for it, or maybe the goal that it's aiming for:

What's the point of this meeting anyway?

I just don't see what the point of (something) is.

This is another way of saying "I don't see the point of ___", but with more emphasis.