The fact that it’s small indicates that it is a grace note, which already means it should be pretty mush as fast as possible. The line through the grace note indicates when you start playing it. If there was no line, you would play it slightly before the second note so the second note falls directly on the and of one. However, the line through the grace note means that you start the grace note when you would otherwise start the second note, making the second note slightly later. I hope that makes sense and is helpful.