Before I became a teacher, I had never heard of glyphs, either! But I have since learned that a glyph is a visual way of representing information ... sort of like a graph, but typically, a graph only answers one question or shows one fact. With a glyph, you can show up to four, five or more pieces of information at once. For example, this month we did a gingerbread man glyph; each child had a gingerbread cut-out. The key (which I copied big, for the board, plus a smaller one for each table or pair of kids) showed the data they would represent on their cut-out. Our topic was holiday snacks ... so, if they liked chocolate cookies, they were supposed to draw the eyes on their cut-out one way; if they liked sugar cookies, another way, or oatmeal, a third way. If their favorite beverage to drink with cookies was juice, they drew a squiggly mouth; if it was milk, they drew a straight mouth, and so on. Another question was "If you have ever baked Christmas cookies, draw one button. If you haven't, draw two buttons."
So, for kids, it gives them practice in following directions, and then when the glyphs are done and you post them on a big chart, the data can be analyzed. By looking at the cut-outs, kids can answer a variety of questions - for example, do more students in our class like chocolate chip cookies, or sugar cookies? I use them primarily as a math activity in 2nd grade, but with older kids you could do more writing/drawing conclusions work, too. They also can be a good way for kids to practice cutting/fine motor skills, depending on how complicated you want your glyph to be.