Do I need a lexicon?
No. The page’s word note is enough for that sitting. A lexicon is a longer project. It is not required to finish Day 1.
How to read
What a word study on a study page is for
A word study is a short note on one word from the passage: the word, sometimes the original-language form, and the meaning that note is using. It exists so you do not have to pretend you already know the word. It does not outrank the sentence. Read the sentence first, then the word note, then the sentence again. If the page does not show a word study, do not invent a Greek or Hebrew meaning to fill the gap.
What you should see
The word as it appears in the passage you are reading. If an original-language form is included, it is labeled as that form, not as a secret second Bible.
A meaning in ordinary words. If you cannot say that meaning back, you have not used the note yet.
What a single word cannot do
One gloss does not decide a doctrine. The verse still has a subject, a verb, and someone being addressed. The historical-context guide is about that setting. The word note is narrower.
A word study is not a cross-reference. A cross-reference sends you to another passage. A word study stays on this word. Follow one of them at a time.
In your journal
You may write the word and the meaning the page gave you, and then your own sentence about the verse. Mark which sentence is the page’s and which is yours.
If you disagree with the gloss, say what you heard in the verse instead. The disagreement guide is that sitting. Do not swap in a definition you cannot point at.
Questions
What if the sermon never defined the word?
Then you do not have a word study from the sermon. Read the verse in the translation you have. Absence of a gloss is not a hole you have to decorate.