Although explicit instruction is effective in helping second language (L2) learners develop intelligible pronunciation, it is necessary to understand why and how L2 teachers implement such explicit pronunciation instruction systematically in class. Because of its key role in enhancing learners' pronunciation skills, understanding the rationale behind the implementation of explicit instruction by teachers in different contexts is necessary. A key aspect of analysis in the implementation of explicit pronunciation instruction is the teacher's metalanguage knowledge, which could showcase a key component of pronunciation teachers' ability to present phonetic-phonological content in an accessible manner to learners during explicit instruction. This case study analyzed an experienced English-as-a-foreign-language (EFL) teacher's metalanguage knowledge in L2 pronunciation instruction. Using qualitative data-collection methods (e.g., semi-structured interviews, classroom observations, and stimulated-recall interviews), and Freeman's (2020) "Knowledge Base of Language Teaching Framework," the results of this study showcase the way an experienced teacher's metalanguage knowledge influenced the implementation of explicit L2 pronunciation instruction, and how the teacher's metalanguage shaped the type of language available to learners in different activities in class. These results are also discussed in terms of their implications for training teachers in L2 pronunciation pedagogy.