Translate the words into the coastline
Onshore means wind blowing toward the coast; offshore means it blows from land toward the sea. The relationship changes with beach orientation, so a direction that sounds favourable in one bay may mean something different nearby. Use a map and the local forecast together.
Consider the whole visit
An exposed beach can be uncomfortable for someone sitting out a lesson even when another person wants to surf. Think about loose equipment, sand, shade and the walk back. A sheltered break in your day may matter more to your group than a theoretical improvement in wave shape.
Do not use offshore as a safety label
A tidy-looking surface is not an assurance that conditions are appropriate. Discuss wind, swell, currents and your route back with an instructor. If you are planning a different water sport, ask that provider about its specific requirements; advice does not transfer automatically between activities.
Recheck before committing
Forecasts update and conditions change. Look again before travelling and observe from shore when you arrive. If the beach experience no longer suits your plan, choose a land-based alternative and keep the water session for another day.