What Does Brush Tool Mean?

A brush tool is one of the basic tools found in graphic design and editing applications. It is a part of the painting tool set which may also include pencil tools, pen tools, fill color and many others. It allows the user to paint on a picture or photograph with the selected color. The size of the resulting stroke or line and the color can be selected from predefined options, or in some applications the user can create custom definitions. The shape of the brush tool can also be changed to square, circle, oval, and so on, according to preference.

Techopedia Explains Brush Tool

Graphics and image editing programs make extensive use of various painting tools that help in creating new pictures or editing digital images. A brush tool can be used to paint on an image just as a brush is used in reality to paint on a canvas. A brush stroke is made as the user moves the cursor over the image after the necessary selections have been made.