It can mean being attached to something, someone, a situation, an aspect of your life, money, material things, etc
The term itself "being attached" already reveals it!
What do you see when you imagine yourself being physically attached?
A set of ropes or chains constricting you?
In the spiritual field, attachment is often seen as one of the core sources of suffering.
Spiritual teachers often say things like "You have to let go of your possessions and everything you are attached to, lover, career, house!"
They say that the path to spiritual awakening goes through letting go of everything you are attached to.
Why do they say that?
Because attachment keeps you hooked on the material reality.
This is where you put your energy.
It creates as well a fear of losing what you have.
Usually they don't say to "let go of your attachment to your teacher, your tradition or your spiritual practices"
What does that mean?
That usually you replace attachment to the material world by attachment to something more subtle.
You become attached to your daily practice, your Buddha statue or your yoga mat!
You just replace an attachment by another!
However, any attachment creates a certain form of dependence and addiction.
Being addicted to a healthy life style can still be seen as a form of addiction.
I call that positive addiction because it usually makes you happier.
If you are extreme in your attachment, that makes you fanatical!
Fanatics are people who are extremely attached to their spiritual tradition.
You can as well be fanatical about your work or a positive mission.
Being a fanatical is not necessarily negative!
It can be positive!
Those who positively impact on society are usually fanatical about their mission!
The art is to master attachment and fanaticism!
It is not to totally destroy them!
For instance, you can be enslaved by your career goals because you are obsessed with being a high achiever!
This might destroy your health, family and life if you don't watch out!
Fanatical ambition is a powerful fire that can transform the planet!
As with any fire, any energy, the goal is to master it and use it in skillful ways.
You don't want your passion to lead to destruction!
Same with attachment!
Defend your territory when it is wise to do so!
Sometimes you must fight for what's yours!
Sometimes you must let go!
If everyone was letting go if everything all the time, the planet would be in a mess!
On the other hand being attached to a sinking boat leads to self annihilation.
So it's not so much attachment or fanaticism that are good or bad, it is the way you use these qualities!
Next time someone says that detachment leads to awakening, check it out!
What is really being said?
Question it and develop your own truth around it.