What does 1 Chronicles 4:21 mean?

Shelah, Judah’s son, had sons: Er, who started Lecah; Laadah, who started Mareshah; and the families of linen workers at Beth Ashbea. 1 Chronicles 4:21 - Modern Text Bible

(This verse notes the descendants of Shelah and mentions a group known for their work with linen, showing both family and trade connections.)