As artificial intelligence (AI), and especially generative AI, are increasingly impacting daily life, it is becoming essential for learners to acquire AI literacy -- the capability to interact with AI at the interface of technology and the target language. Without AI literacy, they may struggle to navigate AI-driven systems and access benefits of this new technology. Questions of how to define and operationalise AI literacy loom large across the educational sector, but existing approaches generally do not consider the specific needs of language learners. In this conceptual paper, we focus on AI literacy for English language learners -- we critically review existing research on AI literacy, provide an overview of a conceptual model of AI literacy that we have developed for language learning contexts, explain its pedagogical implications, and illustrate the theory in action through two detailed examples of learning units to help English teachers to operationalise the model in their practice.