详细可以看一下help

?"$"

Extract or Replace Parts of an Object
Description
Operators acting on vectors, matrices, arrays and lists to extract or replace parts.

以eps为例说明

?vBEKK.sim

Value

A list of class "mvBEKK.sim" with the following elements: length length of the series simulated

order               order of the BEKK model
params           a vector of the selected parameters
true.params    list of parameters in matrix form
eigenvalues    computed eigenvalues for sum of Kronecker products
uncond.cov.matrix unconditional covariance matrix of the process
white.noise    white noise series used for simulating the process
eps                  a list of simulated series
cor                    list of series of conditional correlations
sd                    list of series of conditional standard deviations

所以知道 eps 是  a list of simulated series

###
sim = mvBEKK.sim(series.count = 3, T =100)
names(sim)
# [1] "length"            "series.count"      "order"             "params"           
# [5] "true.params"       "eigenvalues"       "uncond.cov.matrix" "white.noise"      
# [9] "eps"               "cor"               "sd"

sim$eps
#[[1]]
#  [1] -0.19612661 -0.64480093  1.62395655 -0.33026064 -0.34676227


#[[2]]
#  [1]  1.78685217 -0.62248325  0.96838894  0.73833425  1.66785995


#[[3]]
#  [1] -0.810340036  1.756455758 -1.444400841 -2.353201553 -0.639545512

sim$eps[[1]][1:5]
#[1] -0.1961266 -0.6448009  1.6239565 -0.3302606 -0.3467623

sim$eps[[1]][1:5]

非常感谢epoh大师！
学生还想再问一句：为什么要在[[1]][1:5]中[[1]]要加两对方括号呢？非常感谢！

list的用法是[[1]]