Ring spinning thins out a strand of cotton fibers and twists it tightly as it winds onto a bobbin. The fibers end up well aligned and closely bound, so the yarn can be spun finer and feels smoother against the skin. Jersey knit from it is usually softer, drapes better and has a more even surface than budget open-end fabric.
That even surface helps printing. Fine lines and halftones sit more cleanly, and DTG prints tend to look sharper on a tight ring-spun knit. Ring-spun yarn is often paired with combing, and spec sheets may give the yarn size in singles, where a higher number means a finer yarn.
The trade-off is cost: ring spinning is slower than open-end spinning, so blanks made with it cost more. When comparing tees, look at the yarn type and the fabric weight together. The ring-spun vs open-end guide explains how to read the label.