What happens when the sketch element is identified by a number next to the cursor?

When a sketch element is identified by a number next to the cursor, it indicates that the element's size is exact and no dimensions are needed. This is typically a feature of dimensions in SolidWorks, which allow users to see the size or constraint of the sketch element visually represented as a numerical value. When the value is displayed next to the element, it means that the geometry is defined to a specific measurement and adheres to the constraints set by the user, thereby eliminating the need for further dimensional input.

In a well-defined sketch, each element is either explicitly dimensioned or constrained such that its size and shape are controlled, which is what that numerical indication represents. This is especially useful during the sketching process, as it allows for a clear understanding of the geometry without the clutter of additional dimension lines or numbers.