When we count objects we say: one, two, three… these are called «cardinal numbers». But when we want to arrange things by position, we use different words called «ordinal numbers»: first, second, third, fourth, fifth…
Example: if five children stand in a line, the child at the front is «first», the next one is «second», and so on until «fifth» at the back of the line.
We use ordinal numbers often in daily life, like ranking winners in a race (first place, second place, third place), naming days of the week, or describing which floor of a building we live on.
