I'd like to understand learning disabilities (LD).

A learning disability (LD / specific learning disorder, SLD) is a characteristic in which—despite no overall intellectual delay—there is marked difficulty with specific learning skills such as reading (dyslexia), writing (dysgraphia), or calculation (dyscalculia). It's not a lack of effort or a discipline problem, but a difference in how the brain processes information, and children can learn with the right support. Support centers on reasonable accommodation and environmental adjustment: tablets, text-to-speech and writing alternatives (ICT), larger grids, reduced volume, and using the child's stronger input channels. If you're concerned, an assessment at a specialist service is the starting point for support.