Let's read a query that finds a single specific row out of a whole table.
SELECT * FROM students ORDER BY age DESC LIMIT 1; does two things in sequence, in this order: first ORDER BY age DESC sorts every student from oldest to youngest, then LIMIT 1 keeps only the very first row of that sorted list.
The result is exactly one row: Sara, the oldest student in the table. If a new, older student were added tomorrow, this exact same query would automatically return them instead it always finds "whoever is currently oldest," not a fixed name.
This oldest-student query is a small example of a genuinely common real pattern: "find the top result by some measure" the highest-paid employee, the most recent order, the top-scoring quiz attempt. All of these share the same shape: ORDER BY the measure, then LIMIT 1.
Try changing DESC to nothing (ascending) in your own head LIMIT 1 would then return the youngest student instead. The sort direction is what decides which "top" you actually get.