This most likely means that someone wants to borrow one of your employees or coworkers for a short period of time. For example, if you are working in construction and two of you are pouring concrete while someone else is trying to lift a heavy beam the person lifting the beam may come up to you and ask to borrow the other guy for a spell to help him lift the beam.

google definition "for a spell" https://dictionary.cambridge.org/dictionary/english/spell a period of time for which an activity or condition lasts continuously: I lived in Cairo for a spell. She had a brief spell as captain of the team. I keep having/getting dizzy spells (= periods of feeling as if I'm turning around). ​ a short period of a particular type of weather: a spell of dry weather The weather forecast is for dry, sunny spells.