What does the term stringing mortar mean?

Stringing mortar is the practice of placing mortar over several bed joints before laying the brick units into the mortar. The alternative approach would be to lay just enough mortar to place each brick. The length of mortar that can be strung depends on the weather. During hot, dry days, you must keep the length of the mortar placed on the bed joints to a minimum to prevent the mortar from drying out before you lay the brick units.