Lexis and structure make up a language. Words are sounds that are combined in particular ways to project a message (physical/mental), and structures are how words are arranged to convey thoughts.
Is it enough if we know what a word means? (meaning) While speaking, words are pronounced (pronunciation and stress) and while writing, words are spelt (spelling). We also need to know its form—a noun or verb and also its role—noun as a noun or verb (word class). We need to know the letters that we can attach to make more words (affixes). Certain words usually combine with certain other words (collocations). Words can give negative or positive colour in addition to their denotations (connotations). It’s good to know other words that can replace a given word without altering its basic meaning [synonyms (antonyms)]. We need to learn how to arrange words in a given order (SVO/C/A) and how and what they combine with (patterns VNN/V-ing/to-infinitive or word with particles/prepositions). Equally important it is to know where a word can be used or may not be used (speaker-listener relationship—formal or informal).
A non-native learner doesn’t have the benefit of a live society to pick up words in their several aspects. The teacher and the coursebooks are their major resources. They listen to the teacher, read the coursebooks, practise in speaking, reading and writing to the best of their ability.
A word can have one meaning or multiple meanings. This can be learnt only through courebooks and the use of a dictionary. Non-native learners get to learn pronunciation and syllable stress from their class teacher (aural-oral)---‘photography’ and ‘photograph’, ‘content’ as noun and adjective), master spelling through the eye and the hand –‘scene’ and ‘seen’, learn to identify their brand and their role. Practice enables them to form more words through prefixes and suffixes--employ, employed, employer, employee, employable, employment, unemployable, unemployed, unemployment. With time, they learn and appreciate collocations: ‘bear the brunt of’, ‘on the brink of defeat’, connotations like ‘slim, skinny, lean, thin’, ‘slender’, ‘stare, glare, look, see’, synonyms like ‘ignore’, ‘disregard, ‘neglect’, verb, noun, adjective patterns, simple, compound, complex. And then of course learn to differentiate between formal and informal relationships and how they influence our choice of lexis and structure.
However, classroom learning can only do so much. For instance, meanings, spellings, pronunciation, stress can be consciously learnt. Why, even affixes can be gathered. But collocations, connotations, structures? Learning synonym bunches can mislead for most synonyms are only synonymous and a hundred percent replacement is a rarity. The relationship context cannot be replicated in the classroom.
Learning all these (ten) aspects of umpteen words, internalising them within the limited classroom environment is going to be a touch ask in a non-native environment. Listening to and taking part in genuine day-to-day conversations is next to impossible, especially in the case of learners who go through the formal curriculum in their regional language. While pronunciation and word stress can pose a problem, watching films and reading fiction and non-fiction can be good substitutes as far as using English for all practical purposes is concerned. Here the subconscious comes into play and absorbs like a sponge, stores knowledge and offers us the right lexis and structure when speaking or writing, to our own surprise.
The ratio between the conscious and the subconscious should be in the range of 30:70.