To recognize the text of an image, you need to use the OCR feature. You can find more information in the "Optical Character Recognition" help topic. Also, there's a sample project located in the '<TestComplete>\Samples\Scripts\OCR' directory.
To save data to Excel, you need to obtain its COM object (Excel.Application) in your script by using the Sys.OleObject method and use properties and methods provided by the Excel COM server to interact with its documents. Please refer to the VBA reference shipped with Excel for information on working with it via COM.