• Cognitive-psycholinguistic foundations frame second-language learning as development of language-competence guided by universal cognitive mechanisms, highlighting cross-language transfer, parallel first/second language trajectories, and maturation effects. [3], [4], [6], [7], [15].

• Attitude, motivation, affect, and sociolinguistic context emerge as central drivers of SLA outcomes, linking learner dispositions to engagement, classroom experience, and bilingual schooling effects across communities. [2], [9], [10], [18], [20].

• Learner errors, strategies, and avoidance patterns illuminate how learners negotiate form and meaning, adapt strategies, and progress, illustrating error-driven learning and strategic uptake. [8], [12], [16], [17].

• Bilingual education and sociolinguistic context shape SLA via classroom typologies, community bilingualism, and policy-driven school practices, influencing identity and linguistic outcomes. [9], [11], [18], [20].

• Developmental sequencing and maturational constraints reveal ordered progression and naturalistic sequences in child SLA, with cross-language interactions guiding acquisition pace. [3], [4], [14], [15].