He likely meant an 18% Layer Feed, which will mean it's 18% protein and the 'Layer' refers to a specific phosphorus and calcium content so the girls are sure to have strong shells without leeching calcium out of their bones.
Layer feed is for hens that are laying because it has a higher percentage of calcium in it. It's usually about 16%
I use a start and grow feed that is 20% protein, but only 1.5% calcium so I offer oyster shell for the laying hens which gives them the extra calcium they need. If you have laying hens with younger birds, those younger birds can not eat feed high in calcium.