BigQuery organizes data as project, dataset and table. Here the project is lumen-coffee, a coffee roaster, with datasets shop, raw and analytics_301245 in the Explorer on the left.
A query names its tables with that path: lumen-coffee.shop.orders. The project ID has a hyphen, so wrap the whole path in backticks: `lumen-coffee.shop.orders`. Inside the current project you can leave the project out and write shop.orders, but never the dataset: BigQuery has no current dataset.
Before you run anything, the line to the right of RUN says how much data the query will process. You pay for those bytes, so it's worth watching. Then RUN (or Cmd+Enter) runs it and Query results shows the rows. A column with no name gets one from BigQuery: f0_, f1_ and so on, so give your columns names with AS.