The SystemVerilog features I use in synthesisable RTL: always_ff and always_comb, unique and priority, packages, enums and structs, and what synthesis does with each.
Browsing: System Verilog
SystemVerilog data types explained: logic vs bit, 2-state and 4-state types, enums, packed structs and unions, packed vs unpacked arrays, dynamic arrays, queues and associative arrays.
What SystemVerilog is, how it extends Verilog for RTL design and verification, a short history, what each role needs to learn, and a learning path.