Your wording isn't confusing. This is a very difficult text. Interpretation of it is not certain at all. Not at all. Let's roll through some of it.

First, we know that though all sin is sin, some sins are greater than others (John 19.11; Ezekiel 23.11; Matt. 11.22)

v. 16. Who is the "brother"? Some say it's true believers, some only professing believers (fakers), and some say "your neighbor" (referring to non-Christians). If we can't decide on [i]that[/i], we're not in a good place to interpret the text.

"the sin that does not lead to death." Is he talking about physical death or spiritual death? He's probably talking about eternal (spiritual) death. Jesus, Luke, Paul, and John seem to separate classes of sins (blasphemy of the Holy Spirit vs. other blasphemy; 1 Cor. 5.45; 11.30; Mt. 18.18-20; Acts 13.8-12; here), but we don't really know the categories.

All sin is sin (1 Jn. 5.17), but some are worse than others and fall into different classes. By v. 18 John seems to be saying that continuing in sin without repentance is the sin that leads to death. It's really impossible to know.

I was confused because I tried looking it up, is this in reference to the idea of “never being able to lose salvation” or what does it mean by the situation of there being sin that does not and does lead to death? Sorry if my wording is confusing. ;)