This stamp, designed by Lim An-ling, was issued on 11 October 2018, and belongs to a set of four that you can see here.
This is the description of the stamps on the Singapore Post site:
Nineteenth-century Singapore was a vibrant commercial centre. But beneath the prosperity, Singapore remained undeveloped in many areas including education. There was little public demand for formal education and the government in British India at that time was unwilling to channel money into developing education, much less the education of girls.
This stamp issue depicts the early education and skills that girls received in Singapore.