An automation is only as useful as the data it can reach. Most workflows read information from one place, reshape it, and write it somewhere else: a form answer lands in a spreadsheet, a new customer is added to a CRM, a support ticket is looked up in a database. Before you connect anything, you need to understand how data is passed from step to step, which is almost always as JSON items with fields you can read and combine.
Connecting two apps also means giving one of them permission to use the other. That is the job of authorization, and most modern services use OAuth 2.0 for it. You will see why the "Connect with Google" button works the way it does, what scopes and tokens are, and why a credential that is set up wrongly is the most common reason an integration fails.
Finally, you will work with the places data actually lives: spreadsheets, business apps, and databases. A basic grasp of tables and SQL lets you read and write records reliably when a spreadsheet is no longer enough. Watch the lessons in order, then continue on to Knowledge & RAG.
n8n's own lesson on how data moves between steps: JSON objects and lists, items as the input and output of every node, and expressions that read and reshape fields.
Nate Barbettini explains how one app gets permission to use your data in another, covering grant types, flows, scopes, and tokens. The same ideas sit behind every "Connect with Google" credential you add to a workflow.
freeCodeCamp's course on connecting real services in n8n: a form that writes to Google Sheets with OAuth2 credentials, plus Google Drive, Google Calendar, WhatsApp, webhooks, the HTTP Request node, and the Code node. It is a long course, so focus on the Google Sheets and credentials parts first.
Mike Dane's freeCodeCamp course on relational databases and SQL: creating tables, inserting and querying data, and joining tables together. It uses MySQL, but the core ideas carry over to other databases you will connect to.