Sometimes the content of cells in the same table column differs in format. For example, it might sometimes be empty, sometimes contain "Bob" (first name) and sometimes "Bob Smith" (first name and last name).
One way, and probably the simplest way, to deal with content irregularities is to use the If Then data converter in the step doing the extraction of some value. You configure its "If" and "Else If" properties so that they match each format variation. The corresponding "Then" properties then extract the matching subpattern.
However, for the "Bob Smith" case, which contains two values (first name and last name), you need to create two steps: one that extracts the first name and one that extracts the last name. This is because the Extract action only allows you to extract one value. Each of the two steps would then contain an Extract action with an If Then data converter so that the first step extracts the first name (if any), and the second step extracts the last name (if any).