TA is the acronym that is used for Technical-Analysis.
Technical Analysis is an analytical method used to predict price action of an asset based on past market data such as price and volume. Technical Analysis uses many tools known as indicators to help boost its likelihood of accuracy. Typically the entire analysis is conducted from a single screen and on a single chart.
Using technical analysis is more commonplace for trading rather than investing, investing require long term thinking, where trading require highly agile short-term capital maneuvering. Optimal strategies leverage both.
TA is commonly used to detect weather prices are in oversold, overbought, or neutral territory.