Blockspring is a service that allows you to use 'blocks' in the app. A block is part of the Blockspring library and is usually based on an external service. You can add many services to the app that aren't directly supported as plugins in Bubble. Use Blockspring to define your own blocks in code, such as JS, R, Python, Ruby, etc. This is a way to run custom code in the Bubble app.
After you authenticate with Blockspring in the Plugins Tab, add blocks to the app. Search by service, keywords, or choose one of your favorite blocks as defined in Blockspring. A block can either be a data source, in which case it will show up in the list of APIs in 'Get data from API' or as actions in the Plugins section of the Action menu. If a block is a data source, you can display the results in a repeating group, etc., exactly as any other built-in plugin. The list of properties is different for each block because each call will have different parameters.
When adding a new block, a popup will open when you set up the block within the Blockspring dashboard. This may include authenticating with the service that a given block is using. Run the block to make sure you get the expected results, and then click 'Use in Bubble' to return to the Bubble Editor. The block is then ready to use as another Bubble plugin!
If you feel the fields returned by your block aren't of the right type, click 'Update fields' and change the type of data. For example, if a block returns a number, but it's marked as a text, you will not be able to use number features on that value. For blocks that return addresses as two numbers, e.g., longitude and latitude, define which fields contain both information, and Bubble will create a new field that contains the computed address, which then can be displayed on a map, etc.