Do red onions don't have seeds?

There are NO seeds inside the onions, but onions (like every other vegetables) bloom and have flowers and from the flowers you get the seeds. If you plant an onion that has roots it will produce a flower and seeds. Read this if you want to collect onion seeds

Onions are bulbs - basically swollen stems - which store up the nutrients for the following year (mostly sugars). They can reproduce either by producing offsets (shoots from the base) which grow into small plants which will come to maturity the following year or by growing to full height, flowering and producing seeds. Once they have flowered, they are no use to us as food but the seeds will germinate and grow into onions which will be edible, of course. If you planted the little onion you show in your photograph, it would grow and probably flower. You could collect the seeds and plant them and they would grow . If you harvested those plants before they developed bulbs, you would have scallions or spring onions and if you let them grow, they would fatten up, the leaves would wither and die and that autumn you'd have a fine crop of red onions. If you left them in the ground, the next year they would flower and the whole thing would happen all over again. Onions are biennials, so they usually grow and make bulbs the first year, lie dormant over winter and then shoot up and make flowers and seeds in the second year.

how long did you stock the onion?

I see you received some good information. I learned something, too!

Onions are bulbs and they have no seeds.

Do you grow it in a chicken egg place?

You get the seeds from the flower from the onion.

Onions and potatoes will sprout when left too long in your pantry. Anna answered this well.

onion seeds are in onions flower not inside the onion.

@May2k8 You can plant them to get more free