Resources
Resources (Rock, Ore, Wood) are used for various things. Building your shelter, upgrading tools, and repairing. These items are useful for survival. It is nearly impossible to beat the game without one of them.
How to get them
Wood
To get wood, you must obtain an axe. The axe can be gained from your campsite. After doing so, press the 'USE' button on the tree {Press 1 on PC}. There will be a spinning sphere. Wait for it to hit the green, then smack the tree with Spacebar Or Clicking the button.
Rock
To gain rock, you must use a hammer, crafted later ingame. Once you press the 'USE' button, there will be a section of red and green. If you want the maximum rock, hit on the green mostly. If you want to get it quickly, spam Spacebar Or Clicking the button.
Ore
To gain ore, you must get a trowel. After that, find the ore and press 'USE' on it. (The Ore is Yellow.) Once done, you will have this slide. If the trowel slides all the way to the end, it will return to the beginning, in an endless loop until you cancel the breaking. You must hit the trowel on the green to get the most loot. Or if you hit the red or orange, you don't get maximum loot.
I hope this all helped!
EXTRAS
If you upgrade your SURVIVALIST skill when you level up, you get way more loot from getting green.