How to dump network requests receive and send?

I want to learn reverse app, I'm confused how to dump network of an app, I tried tcpflow, ngrep, etc. it works but the output data is not human readable, can you give me a linux command to get network receive / send data, from an app / hosts? i try this

sudo ngrep -W byline port 80

ouput

interface: wlp1s0 (192.168.230.0/255.255.255.0)
filter: ( port 80 ) and ((ip || ip6) || (vlan && (ip || ip6)))
####
T 192.168.230.135:29464 -> 91.108.56.124:80 [AP] #4
POST /api HTTP/1.1.
Host: 91.108.56.124:80.
Content-Length: 148.
Content-Type: application/x-www-form-urlencoded.
Connection: Keep-Alive.
Accept-Encoding: gzip, deflate.
Accept-Language: en-US,*.
User-Agent: Mozilla/5.0.
.
.............g[c....x.F$..>o-...O:2..3ib.W.q.._.,.)1.....k.........!..z...M^.g^...I.p...5.yx.Ys...Y*.m.. ....w...uK.%..0....~.f.&...Q..br..W...3..

which is easy to read like a regular text string?