S-V-O+吗 can express yes-or-no question.

Examples:

1. 他 说 汉语 吗？  ta1 shuo1 han4yu3 ma?    Does he speak Chinese?
2. 你 吃 辣 吗？  Ni3 chi1 la4 ma?    Do you eat spicy food?

However, when we do not need "吗", if you want to ask question, you should know the below rules.

1). When you meet "X不X" structure, do not use "吗".
     For examples:
            他 说不说 汉语？  ta1 shuo1bushuo1 han4yu3?    Does she speak Chinese?
            你 吃不吃 辣？  ni3 chi1buchi1 la4?    Do you eat spicy food?

2). When you use question words, do not use "吗".
     For examples:
            你 叫 什么 名字？  ni3 jiao4 shen2me ming2zi?    What is your name?
            你 吃 什么 菜？  Ni3 chi1 shen2me cai4?    What food do you eat?
            "什么" is a question word, so you do not need "吗".

3). When you use "还是"(hai2shi4, or) to express alternative question, do not use "吗".
     For examples:
            他 说 汉语 还是 英语？  ta1 shuo1 han4yu3 hai2shi4 ying1yu3?    Does he speak Chinese or English?
            你 吃 米饭 还是 面条？  ni3 chi1 mi3fan4 hai2shi4 mian4tiao2?    Do you eat rice or noodle?

Related content: Learn Chinese Grammar –Basic sentence pattern