Due to the sticky mucus the snail can climb up walls and roofs with the same speed they have on the ground. 
They can also ignore difficult terrain due to their mucus helping them keeping their footing.

Snails constantly produce slime and mucus to keep from drying and being able to move freely, and when necessary they can spit this slime at a medium or smaller creature to restrain them, this slime almost completely covers their bodies, and restrains them for one minute, the creature can do a dc 12 constitution saving throw when hit, and at the end of each its turns to free themselves from the slime.

If the snail misses the enemy it covers a 5 ft square on the ground, becoming difficult terrain for all creatures on the ground except snails.

Snails often do this if they need to burrow and hide from predators they can't run away from.

Snails are wise and see the good in following laws and being good to others, but most of these ideas derives from their belief in a snail god, and those who don't believe often turn evil, or mind their own business.

The first two centuries of a snail mans life are under water or in deep caves, and at this point they are 2-3 feet tall.

In their late centuries and the rest of their lives they grow bigger and bigger until they reach a height of 5 feet.

Snails live for a very long time, and during their lives most snails find comfort in studying and learning the secrets of the nature or the arcane arts.

Some snails realize in their early adulthood that they want to do their own thing in life, and it is not uncommon for snail men to become wandering merchants or traveling adventurers.

Snail men study a whole lot during their lives, and languages are one of the first things a snail man would consider learning. You gain one extra language.

The snail shell is formed of a strong substance that can break if pushed too hard, but will regrow after a week.
The snail man can hide inside this shell to gain an extra +5 AC as a reaction

From their studying the snail men gain +2 INT, and +1 WIS modifier.

The snail men are known for their study of the arcane

Snail men have so slippery skin that most clubs and fists often slip straight off their skin.