Slugs are shell-less snails. They are terrestrial gastropod molluscs that leave behind a slimy trail. They creep all over your plants. They eat the leaves on the plants in your gardens. They are hard to discourage.
When an area around your home becomes too moist, that moisture creates an environment that entices the slug to make your garden his home.
To discourage the slug and protect your plants you can do several things. You can purchase slug bait in hopes of killing off the slug population. You can place gritty sand or small gravel around your plants. They slug will not be able to travel on the sand or rock.
Or you can place a small container of beer in the area where you are seeing the slimy trail or the holes in the leaves of your plants. The slug is attracted to the beer and when they crawl into the bowl they drown. You can then toss the old beer and the slugs out with the trash.
Another thing to consider is why the slug is chewing on your plants. Most of the time there is too much moisture in the area. You could consider transplanting some of the plants in order to increase the circulation of air in that particular location. Slugs have to have moisture in order to survive. Clearing out a bed will help decrease or stop the damage slugs can do.