What is the meaning of the prohibition of wearing sewn garments during Ihram, and does that include shoes that have laces to tighten them on the foot?

The "sewn garment" prohibited in ihram refers to what is tailored to the body, not everything that contains thread. A pilgrim in ihram is permitted to wear sandals, even if they have straps. However, wearing khuffs (leather socks or boots) is prohibited, unless one cannot find sandals, in which case it is permissible to wear them after cutting them below the ankles, according to the preponderant opinion of the scholars. The majority of scholars have cited the Prophet's ﷺ hadith, narrated by Al-Bukhari and Muslim, as evidence for the requirement of cutting them. As for women, they are permitted to wear khuffs absolutely.