"That woman looks nice"
Translation:Mwanamke yule amependeza
I can answer the part about the object infix. The woman is the subject, not the object. The verb -pendeza is the causative of -penda, so it's basically "to cause to like/love", or in other words "to be lovely" etc. The person who is caused to love is the object, so you could use the object prefix -ni- (it's not technically an infix as they say in the course) to say "That woman looks nice to me". If you use -m- you're basically saying "That woman looks nice to him/her."
I'm not so sure about the -me- but it's often used in sentences that translate to the present states in English because the equivalent verbs in Swahili are generally dynamic. For example -lewa is "to get/become drunk" and not really "to be drunk". If you want to say "I am drunk," you basically say "I have become drunk" Nimelewa ... the -me- expressly makes clear that the consequences of the past getting drunk are still true, so it's essentially equivalent to saying that you are drunk. I suppose it could be like that with -pendeza as well, but it seems a bit less logical to me and I'm pretty sure I've seen it used with -na- a lot just to indicate that someone is attractive/nice/likeable ... but my experience of Swahili is pretty much limited to what's on the internet, so I'm not a good source for this.