WiFi signals are deliberately designed to be short range (around 100' in clear space) to minimise interference. If you are near a WiFi source then the eqt above will help you get a better signal from a bit further away (probably only about 50-100mtrs max).
WiFi sources are available at some pubs, restaurants, camp sites etc. If you have BT Broadband & agree to share your own wifi signal then you can access all other BT Broadband "hot spots" which is probably 20% of all residential broadband customers.
BT is free to BT customers, but can be accessed by anyone for a charge. Most pubs, campsites & restaurants are also free altho some charge & you will always need an access code, just ask for it.
It is effectively a small amplifier. I can access my own BB at the bottom of the garden (about 100' from the house) but not without the amp. You can also add a more powerful aerial (directional are strongest if aligned correctly) and they can be mast mounted like TV aerial to pull in a signal fromup to about 1km away. This will cost around 20-50 quid extra.
Distances are very approx as trees, walls, buildings & other vans etc can kill a signal quite quickly.
Hope that helps, ask again if it doesn't.