A strainer is a kitchen tool full of little holes: you pour something through it, the liquid runs out and the solid bits stay behind. A tea strainer catches the leaves; a big one catches the noodles when you pour away the hot water. It is usually a bowl or cone of wire mesh or perforated metal or plastic, often with a handle. The related word is 'colander' — a colander is the bigger bowl with larger holes that you tip pasta or washed vegetables into; a strainer is generally finer and smaller. But people are loose about this in real kitchens, and plenty of speakers call both a strainer. Outside the kitchen, the same word is used for filters in machines and water pipes — an oil strainer, a pump strainer. Note that the everyday verb for using one is not usually 'strainer' anything; you 'strain' the tea, or you 'drain' the pasta, and 'drain' is the word most people reach for at the sink.