What is load balancing in a router?

Question

Load balancing

There was a problem with the Internet in the office. The speed is not always enough, and the quality of the Internet is also not very good.
Now we just manually poke cables from 2 different providers in the router, if there is a problem with one.
I would like to automate this process somehow.
Speeds of 100 Mb., You need more, but providers do not provide.
I'm thinking about Cisco RV042G.
Do I understand correctly that if I plug 2 vans into it with 100 MB each, then there will be 200 in the LAN?
Or will it only turn out to make a backup channel, that if one is lost, then the second one is automatically connected, so as not to run and change wires?
Moreover, it happens that the Internet seems to be there, but it is very buggy, then the site loads for 5 minutes, then Skype video does not work. Will it be possible to configure that this behavior also switched to the backup channel?