Diagram label completion asks you to label parts of a picture — a machine, a process, a place — with words from the passage, inside the printed word limit. Read the labels and the empty boxes first so you know what kind of word fits: a part, a material, a direction. Then find the paragraph that describes that object. Copy the word that names the part; a nearby noun from the next stage is a common wrong label. This is not flowchart completion, which is a sequence of steps in boxes, and not a Task 1 diagram you write. Do not invent a label from general knowledge. The paper is about 60 minutes. Practice IELTS is Writing and Reading only. Scores are practice estimates, not official bands.
Take 1 free scored test (Writing or Reading) at https://practice-ielts.com. Then $14.99 for 3 months of Writing + Reading. Not official IELTS.