Veda Vyasa compiled the shruthi (eternal sounds captured by the sages) into the Vedas. The Vedas talks about Bhagavan, the ultimate God. Vedavyasa distilled the Vedas into cryptic aphorism (bite-size phrases). The Brahmasutras remained confusing for the general masses. Ramanucharya created the Sri Bhasya to explain the meaning of the Brahmasutras.
Sri Bhasya Summary
athāto brahma jijñāsā, janmādy asya yato, shastra yonitvat, tata Samanvayat. Then, therefore, I want to inquire about Brahman. The one who creates, sustains, and destroys is the Brahman. Bhagavan is understood through the shastras. You will achieve Bhagavan and Bhagavan is always bigger.
Rahasyatrayasaram
The Sri Bhasyam shows the difficulty in understanding and reaching Bhagavan by the Vedic routes outlined in the 31 brahmavidyas of the Updanishads. Very difficult. He then explains the greatest gift to humanity - prapatti - as the means to achieve salvation for even the ones not qualified to perform bhakti yoga. This is outlined in the rahasyatrayasaram.
Vishistadvaitam
Three schools of philosophical thought arise from the Vedas: advita, dvaita, and vashistadvaita. Ramanujacharya explains that the nature of reality is three things: chit (souls of the nature of knowledge), achit (material - not of the nature of knowledge), iswara (God). Unlike advaita (I am the God) and dvaitam (I am of the God), Vashitadvaita says I am for the God. The jivatma and paramatma (God) are distict but cannot be separated.
Yoga in a nutshell
karma yoga - doing all the karma (ordained duties) without any attachment. jnana yoga - understanding that there is no difference between white paper and 100 dollar bill. bhakthi yoga - always doing prayer and dedication to bhagavan.