Fetching details from the dictionary...

to (call and) stop; to call (someone) to stop; to hail (e.g. a taxi)
走り去ろうとする子供を呼止めて注意した。
I stopped the child who was about to run off and gave a warning.
彼女は立ち去る友人を呼止めた。
She called out and stopped her friend who was leaving.
受付係が廊下で来客を呼止めている。
The receptionist is stopping a visitor in the hallway.