This is the 4534th most frequent Swedish word.
yngsta
"Yngsta" means "youngest" in English.
Here, 'yngsta' is used as a superlative adjective describing 'den', which refers to 'Hon'. It denotes the youngest individual in a specific group.
Hon är den yngsta i klassen.
She is the youngest in the class.
In this sentence, 'yngsta' appears as a superlative adjective modifying the word 'barn', specifying the child among others who is the youngest.
Hans yngsta barn gillar att läsa böcker.
His youngest child likes to read books.
Here, 'yngsta' is applied to denote a subgroup within 'deltagarna' identified by their youngest age.