Higher values will keep images closer to the prompt
The Guidance slider allows you to add more weight to your overall prompt. If you want your output to more closely follow your prompt, increase the guidance.
The trained style of the Model is also heavily effected by the Guidance slider. Although increasing the Guidance will make the output adhere more closely to your prompt, if you push the guidance slider too far the image will begin to degrade.
When guidance is getting too high you'll notice 'saturated' or 'plastic' looking outputs
When guidance is too low you'll notice more abstract or unpredictable results.
"Good Guidance" will not always be the same number on the slider. Every model and prompt can have a different sweet spot.