Shauca—Purity, Santosa—Contentment, Tapas—Austerity, Svaadhyaaya—self-study (which leads to knowledge of the Self), Ishvara-pranidhaana—Surrender to the Lord are the Niyamas, the internal observances.
Whereas the Yamas are restraints enjoined on the Yogi in order to not be a disturbance to others and be in harmony with the world, the Niyamas are internally directed to develop self-discipline. The Niyamas build individual character and are the bedrock for an orderly life which is a pre-requisite for Self-Realization.
Our character matters far more than any of our circumstances. Who we are is more important than what we are doing. Where you go can truly only go as far as your character can support you. This applies in all dimensions of your life.
The individual Yamas and Niyamas including their attainment and perfections will be discussed in more details in Verses 35 to 45 of this Chapter 2 of the Yoga Sutras.