Most first-time driver’s license applicants must take and pass a Knowledge Exam consisting of a Road Signs and Road Rules test.  All information you need to pass this test can be found in the Driver’s Manual. 

There are many sites that have practice tests. Each of them has questions that are similar to the questions you will find on the actual test.  Visit more than one of them to get lots of practice.
DPS siteinternetforms/Forms/DL-7.pdf84 questions in Appendix C of Drivers Manual
www.driversedguru.comquiz-18 tests with about 25 questions each
Driver License Test Texas Appplay.google.com/store> 150 questions
teentexasdriving.comTexas-Teen-Driver-Education/dmv-practice-test 
quizlet.com84-texas-dps-permit-review-questions-flash-cardsAbout 84 questions