TensorFlow in python is a library developed by Google for faster numerical computations in Deep Learning. TensorFlow is used in building machine learning models using high-level APIs like Keras. TensorFlow library makes it easy to train and deploy models on the cloud, browser, or any device. TensorFlow is used to build deep learning models for image recognition, RNN, seq2seq models for machine translation, etc.
If you are interested to learn TensorFlow, I recommend this Artificial Intelligence course by Intellipaat.
You can watch this video on TensorFlow in 10 minutes to know more about TensorFlow: