He is referring to sauces that you put into a CO 2 (Carbon Dioxide) cannister, then spray onto plates to give the sauce a lighter, foamy texture.
For your raspberry sauce, I would recommend making a raspberry creme anglaise or coulis. However, you need to strain your coulis very well before adding it to the cannister, or else the seeds will clog it up. Also, don't make either of the sauces too thick or else you won't be able to get enough air into them.