十字路口(shí zì lù kǒu) - crossroads in Mandarin

十字路口 (shízìlùkǒu) means "crossroads". 十字 (shízì) is "the character 十 (shí)", which is shaped like a cross, and 路口 (lùkǒu) is "road opening, junction", so the compound literally describes a junction shaped like the character 十 (shí): two roads crossing at right angles.

It is a direction-giving essential: 在十字路口右转 (zài shízìlùkǒu yòu zhuǎn), "turn right at the crossroads", is the kind of instruction you will hear from a taxi driver or give a friend meeting you in town.

路口 (lùkǒu) alone, without 十字 (shízì), just means "junction, intersection" in general and covers T-junctions and forks too, not only four-way crossings. Use 十字路口 (shízìlùkǒu) specifically when the crossing really is a cross shape; otherwise plain 路口 (lùkǒu) is the safer, more general word.