What is meant by resolution?

For all pixel graphics, such as images or print data created with image editing programs like Photoshop, a sufficiently high resolution is crucial. Depending on the print product, the resolution of your layout as well as all included graphics and images should ideally be between 100 and 300 dpi.

What is the difference between a pixel and a vector graphic?
https://www.myfolie.com/de/faq/was-ist-der-unterschied-zwischen-einer-pixel-und-vektorgrafik/

What are DPI and what do you need to know about them?
https://www.myfolie.com/de/faq/was-sind-dpi-und-was-muss-man-dazu-wissen/