Hello MollyB,
Charles was in the Royal Engineers, Sapper, Service No. 122225.
He was awarded the 1914/15 Star, British War Medal and Victory Medal. The numbers next to the medals are roll references which can be looked up at the National Archives and sometimes give a bit more information, such as the actual unit he served in.
He was awarded the Star because he entered the theatre of war (France and Flanders) between Nov 1914 and Dec 1915. In his case it was 30th October 1915.
For some reason the Star was re-issued, but I can't read why, possibly because the wording was wrong. I don't know what the other codes on the right hand side stand for.
http://www.nationalarchives.gov.uk/documentsonline/medals.asp gives an explanation of the various medals.
You will also find more information on him at the CWGC using this link:
http://www.cwgc.org/search/casualty_details.aspx?casualty=471320Phil