If we want to keep what is on the left, we can use the LEFT function in combination with SEARCH tell it when to stop extracting.
For example, you can use =LEFT(cellname,SEARCH("-",cellname)-2) to turn Some Good Text - Followed By Garbage into Some Good Text.
You can also use =RIGHT(cellname, LEN(cellname) - FIND("-", cellname)-1) to turn Garbage - Followed by Good Text into Followed by Good Text.
LEFT or RIGHT dictates which direction to extract from. They both require 2 values: the cellname and how much to extract.
The second value depends on the cell contents, so we use SEARCH to find the split point (hyphen) and then remove 1 or 2 cells to remove the spaces around the hyphen.