Regular expressions (regex) are powerful tools that enable developers to efficiently search, match, and manipulate patterns within text strings, enhancing coding workflows significantly. Unlike manually iterating through characters to count spaces or words, regex simplifies these tasks with concise patterns, allowing for dynamic text processing applicable across various programming languages. The lesson demonstrates how to implement regex in Go to create a straightforward word counting algorithm, using the regex package for practicality. It covers key techniques such as defining patterns for word and space detection, utilizing capture groups for extracting specific data like email domains, and performing text replacements based on matched criteria. With a recommendation to consult resources for mastering regex syntax, the discussion emphasizes the versatility and efficiency regex brings to string handling tasks in programming.