First, you must link the apaleo's hotels/properties to a Xero's organisation. You can do that in the menu "Xero organisation config". You see all your apaleo's property in the list. In the column "Organisation" you can select the appropriate xero's organisation. (If you don't see all your xero's organisations in the list, try the menu "Reconnect Xero" and add by login the missing organisations. You can add by login only one organisation. If you need to add more organisations, you must try the menu "Reconnect Xero" more times.) You can link more apaleo's properties to one xero's organisation, or you can do 1:1 mapping.
Additionally, you can define a xero property name for each property. This information will be sent with each transaction. The "Property Name" is a tracking category in xero.
The name of the tracking category can be defined in the field "Tracking category in Xero".
With the checkbox "Don't send transactions with the same debitory and creditory account" you can manage, which transactions will be sent to xero. You can find more information about the topic on the page Converting apaleo's bookings to xero.