Abarim Publications' online Biblical Hebrew Dictionary
As a verb, this root תלם (tlm) doesn't occur in the Bible, so we don't know what it means. But its sole derivative is the similar noun תלם (telem), which means furrow (Job 39:10, Psalm 65:10), which suggests that the parental verb has to do with plowing and tilling the soil.
The form תלם (telem) also occurs as a defective plural of the word תל (tel), meaning mount or heap. This particular plural occurs in Joshua 11:13.