One webpage about Judaism describes it this way:
The mindset for prayer is referred to as kavanah, which is generally translated as "concentration" or "intent." The minimum level of kavanah is an awareness that one is speaking to G_d and an intention to fulfill the obligation to pray. If you do not have this minimal level of kavanah, then you are not praying; you are merely reading. In addition, it is preferred that you have a mind free from other thoughts, that you know and understand what you are praying about and that you think about the meaning of the prayer.I think this delightful concept is a treasure we need to explore more deeply as Catholics. When we celebrate the Mass, whether as presider, liturgical minister, or as a member of the assembly, we should have that kind of interior intentional focus. De musica sacra et sacra liturgia (Instruction on Sacred Music and Sacred Liturgy) written in 1958, at the time when the concept of "active participation" was first being universallly promoted, puts the concept this way:
22. By its very nature, the Mass requires that all present take part in it, each having a particular function.53 years on, it is possible that we may have lost the original balance between interior and exterior participation. We focus on asking people to sing, to say the prayers, etc, but I see very little evidence that in our catechesis of children, youth and adults that we more than sporadically make an effort to help people understand what should be going on in their mind and heart during Mass. To be sure, most people who are willingly at Mass naturally make an effort to be involved in what is happening during the liturgy. They sing, sit, stand, process, and listen. However, are they doing kavanah? Are their minds free of other thoughts? Do they understand what they are praying about, and do they think about the meaning of the prayer?
a) Interior participation is the most important; this consists in paying devout attention, and in lifting up the heart to God in prayer. In this way the faithful "are intimately joined with their High Priest...and together with Him, and through Him offer (the Sacrifice), making themselves one with Him" (Mediator Dei, Nov. 20, 1947: AAS 39  552).
b) The participation of the congregation becomes more complete, however, when, in addition to this interior disposition, exterior participation is manifested by external acts, such as bodily position (kneeling, standing, sitting), ceremonial signs, and especially responses, prayers, and singing.
When we begin using the Third Edition of the Roman Missal in the coming months, will people be engaged more deeply because they now have to think about the words? Or will they be put off by long, complex sentences and difficult words? I am convinced that the quality of interior engagement with the liturgy in the months and years to come will be due to the quality of the catechesis provided to people on the new Missal.