In a previous article  we presented an overview of the instrument "Test of Understanding of Vectors" (TUV) in English that evaluates students' understanding in vector concepts. This test was originally designed by us in Spanish (TUV-Spanish) and afterwards in English. The three objectives of this study are: 1) to present the test in Spanish and its design process, 2) to show that it is a reliable evaluation instrument with satisfactory discriminatory power following the analyses recommended by Ding et al. , and 3) to analyze the understanding in each of the vector concepts evaluated in the test of 585 students completing the introductory physics courses in a private Mexican university. The article has diverse implications. The design process and the reliable analyses presented in the article can be used by researchers that want to design multiple-choice tests. On the other hand, the analysis of students' understanding and the test in Spanish (that is included at the end of the article) can be employed by physics teachers that teaches vector concepts in Spanish-speaking countries.