In plain words
In the lotus of the heart there is an awareness whose very form is 'I'. It is pure, and it does not move. When the ego that rises up is removed, that same awareness gives the happiness of liberation. Be certain of this.
Word for word
The awareness of the form ‘I’ in the heart-lotus is pure and unmoving. Be certain that, through removal of the arising ego, that awareness itself gives liberation's happiness.