Syncing tables will allow you to view table and column names in the dataset editor, as well as use autocomplete when writing SQL. It is recommended that you sync tables when adding a new schema to Explo, or when new tables are added into your database or warehouse.
You can sync tables by clicking on the triple dot menu to the right of the schema.
From here, you can select the specific tables that you plan on querying from while using Explo. Note that all tables will still be accessible in the dataset editor, but only synced tables will show up with autocomplete.
Click continue and the tables should be synced! This may take a little while if the tables are particularly large. Note that a schema only syncs tables taken from the default data source for that schema.