One point which other answers haven't addressed yet is "the delusion of separation" from 'external things'.
I understand that as meaning, for example, "I want a chocolate bar!" (or "I want money", or whatever it is).
And as meaning, "I have no chocolate bar! And I will not be happy, unless/until I get a chocolate bar!"
I might be wrong but I don't think that "delusion of separation" is a normal/standard Buddhist phrase, so maybe I need to guess at what it's talking about.
I guess what it means is that you're thinking, "I am here, and the chocolate is over there, and we are separated." But that separation is a delusion, because what's actually happening is:
- I am here
- I am entertaining a desire for chocolate
- My desire for chocolate is consuming me
- There does exist chocolate and other stuff (and other beings) in the world
The key point is that I and my desire for chocolate are both here in me, not over there in a shop. The chocolate is what it is (e.g. sugary, expensive, wrapped in paper, digestible, etc.). My desire for it (which is what makes it special) is within me, is not from separate me.
Also my desire for it is a property of me, not a property of the chocolate: my desire for chocolate exists because I have indulged in chocolate in the past -- it's not (or is not only) a property inherent in the chocolate. The chocolate isn't thinking, "I am desirable", the desire is yours not of the chocolate. Thinking that the object of the desire is separate is a delusion, partly because the desire is internal, and partly because it may not be a desire that you can satisfy: if you had the chocolate, would you then be satisfied? Or would you need more chocolate?
Wouldn't it be more satisfying to not want chocolate?
So one (of many) techniques of Buddhism would be to think, "OK, I'm thinking of chocolate. But this craving for chocolate isn't much fun. I have better things to do than crave chocolate. I don't want this craving for chocolate. This craving for chocolate is unsatisfactory. I experience distaste for this craving."
And so you decide you don't like the desire. Don't want the desire. And that without the desire you also no longer want the chocolate.
"Chocolate? No thanks! It isn't good for me, it doesn't do anything for me."
I'm going to try to claim that this has introduced two other key Buddhist concepts: i.e. "Anicca" (the pleasure of chocolate would be transient at best), and "Anatta" (I am not a desire for chocolate).
I mention this because it too is not exactly "emotionless". Seeing various desire and saying that the desire are unsatisfactory might be called 'Right view' which is the first step of "Noble eightfold path". The next step, which follows from that view, is 'Right intention' a.k.a. 'Right resolve' which includes 'renunciation'.
And that, 'renunciation', finally provides a way to answer your question: which is about "avoiding attachment". It answers the question because you can use it to begin to look-up reference articles about the corresponding word, e.g. Nekkhamma on Wikipedia, or by searching for 'renunciation' on Access to Insight (press the 'Search' button), which returns many articles such as:
The 'Access to Insight' site, which I referenced immediately above, is a "Theravada Buddhism" site. So its views (the perspectives of the authors of its articles) about the "aim of Buddhism" aren't completely the same as those of other schools of Buddhism, hich are given in e.g. some other answers to this question.
There are several Schools of Buddhism, so when you ask about it or when you "research Buddhism" you might want to be clear about which school you're researching; but see also Basic points unifying Theravāda and Mahāyāna.