On this page of the guide to The Witcher Monster Slayer you will learn how to get new signs that will make battles easier.
You can purchase new signs in the "skills" section. To enter the skills section, you have to click the arrow at the very bottom of the screen (shown in the screenshot above).
The next step will be to press the "skills" icon that appears on the right side of the screen.
Finally, you will need to open the "sign" section and find the two skills called "Aard Sign" and "Quen Sign".
Effect: allows you to deal fire damage.
How to get: available from the beginning of the game.
Effect: deals kinetic damage that stuns the enemy for a second.
How to get: you can purchase it from the skill tree after reaching level 10.
Effect: casting this sign makes you absorb 70% of your opponent's attacks.
How to get: you can purchase it from the skill tree after reaching level 15.