Lucy has just joined the school a few weeks before in S1 and is obviously reluctant to join the other girls at break time.
She seems eager to ask the teacher if she may go into the classroom where she will be on her own and read a book. This is a polite response and may be a perfectly reasonable personal choice, or there could be other reasons for which Lucy needs support.
This guidance teacher knows that Lucy stammers and is now going to monitor Lucy's behaviour to discover whether her stammer is holding her back from making friends. If that turns out to be the case then additional support will be put in place and an approach to a speech and language therapist considered. See also Support for learning: Additional support in this resource.
Evidence from schools and speech and language therapists is that girls are more likely to successfully hide their stammer by just appearing quiet and withdrawn, or avoiding making friends.
As long as academic work is being completed and there are no behavioural traits that cause class management problems, it is tempting for staff to allow the girl to 'quietly get on'. This could mean that an underlying problem is not addressed.