Data row limit for non-delegable queries
This option is purely there to protect your app's performance when it uses connectors that don't support delegable queries, such as the OneDrive Excel connector. A delegable query can be defined as one that pushes the processing load to the data source, rather than downloading all of the data locally to your canvas app and processing it locally.
You may want to change this number, depending on the data that you're going to pull back from your connector. For example, if you know that your data source is going to return 700, you may wish to increase this to ensure that you have all of your data available.
The lowest possible value is 1, which means that 1 item will be pulled back at a time. On the other end of the scale, Microsoft imposes a maximum limit of 2,000, which is purely used to protect the overall performance of your app. Therefore, if you wish to query a data source that is going to pull back more than 2,000 items, then you should consider moving to a connector that supports delegation.