Over the past several decades, applied linguistics and second language (L2) acquisition and teaching have been areas of prolific research and have undergone continual development. The purpose of this article is to identify essential themes in the field of applied linguistics, focusing more intensely on teaching and learning second languages in a classroom setting. Given that the current professional literature enjoys a vast selection of high‐quality, comprehensive books on second language acquisition, the purpose of this article is to provide a concise yet overarching summary of the most pivotal aspects of second language acquisition research and their implementation in L2 teaching. The article provides theoretical background on linguistic factors involved in L2 learning (exposure and input, output, vocabulary, repetition, and automaticity) and extralinguistic factors (attitudes, motivation, culture, and the teaching/learning experience). Following the description of the theoretical background, pedagogical implications are suggested for each of the theoretical points covered. The discussion is situated in the framework of 21st‐century multilingualism in general and translanguaging approaches in particular.