Stats in Kingdom Come: Deliverance are one of the 4 means through which the players can develop their characters. The Stats will increase as you use them throughout the game, much the way they do in Skyrim or Oblivion. Increasing your Stats will also increase your Character Level.
Strength defines how well a character can handle physical challenges.
Agility is a measure of speed, movement and nimbleness.
Vitality determines how much a character can endure.
Speech gauges the character's ability to talk his way out of situations.
Charisma is a measure of how you can impress people.
Visibility is the opposite of camouflage.
Conspicuousness is a measure of how you stand out in the normal environment, i.e. whether or not people who see you will look twice.
The more Noise you make the more likely you are to be discovered whenever you move.
Speed determines how fast you can walk, run and sprint.
Health is a fixed value that cannot be increased. Players will take damage from combat, not eating, falling etc and will need to take a health potion or sleep to replenish it.
Your character's Stamina depletes every time you do something physically demanding, e.g. sprint or fight, and when it drops to zero, you can do neither.
Your character gets tired over time and then it needs to rest. Energy is depleted by combat, movement and basically just by being awake.
Your character needs to eat and drink. Each type of food and drink will fill you up to a greater or lesser extent meat and meat products a lot, fruit and drinks little.